1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoader.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/codeCacheExtensions.hpp"
32 #include "code/scopeDesc.hpp"
33 #include "compiler/compileBroker.hpp"
34 #include "gc/shared/gcLocker.inline.hpp"
35 #include "gc/shared/workgroup.hpp"
36 #include "interpreter/interpreter.hpp"
37 #include "interpreter/linkResolver.hpp"
38 #include "interpreter/oopMapCache.hpp"
39 #include "jvmtifiles/jvmtiEnv.hpp"
40 #include "memory/metaspaceShared.hpp"
41 #include "memory/oopFactory.hpp"
42 #include "memory/universe.inline.hpp"
43 #include "oops/instanceKlass.hpp"
44 #include "oops/objArrayOop.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "oops/symbol.hpp"
47 #include "oops/verifyOopClosure.hpp"
48 #include "prims/jvm_misc.hpp"
49 #include "prims/jvmtiExport.hpp"
50 #include "prims/jvmtiThreadState.hpp"
51 #include "prims/privilegedStack.hpp"
52 #include "runtime/arguments.hpp"
53 #include "runtime/atomic.inline.hpp"
54 #include "runtime/biasedLocking.hpp"
55 #include "runtime/deoptimization.hpp"
56 #include "runtime/fprofiler.hpp"
57 #include "runtime/frame.inline.hpp"
58 #include "runtime/globals.hpp"
59 #include "runtime/init.hpp"
60 #include "runtime/interfaceSupport.hpp"
61 #include "runtime/java.hpp"
62 #include "runtime/javaCalls.hpp"
63 #include "runtime/jniPeriodicChecker.hpp"
64 #include "runtime/memprofiler.hpp"
65 #include "runtime/mutexLocker.hpp"
66 #include "runtime/objectMonitor.hpp"
67 #include "runtime/orderAccess.inline.hpp"
68 #include "runtime/osThread.hpp"
69 #include "runtime/safepoint.hpp"
70 #include "runtime/sharedRuntime.hpp"
71 #include "runtime/statSampler.hpp"
72 #include "runtime/stubRoutines.hpp"
73 #include "runtime/sweeper.hpp"
74 #include "runtime/task.hpp"
75 #include "runtime/thread.inline.hpp"
76 #include "runtime/threadCritical.hpp"
77 #include "runtime/threadLocalStorage.hpp"
78 #include "runtime/vframe.hpp"
79 #include "runtime/vframeArray.hpp"
80 #include "runtime/vframe_hp.hpp"
81 #include "runtime/vmThread.hpp"
82 #include "runtime/vm_operations.hpp"
83 #include "runtime/vm_version.hpp"
84 #include "services/attachListener.hpp"
85 #include "services/management.hpp"
86 #include "services/memTracker.hpp"
87 #include "services/threadService.hpp"
88 #include "trace/traceMacros.hpp"
89 #include "trace/tracing.hpp"
90 #include "utilities/defaultStream.hpp"
91 #include "utilities/dtrace.hpp"
92 #include "utilities/events.hpp"
93 #include "utilities/macros.hpp"
94 #include "utilities/preserveException.hpp"
95 #if INCLUDE_ALL_GCS
96 #include "gc/cms/concurrentMarkSweepThread.hpp"
97 #include "gc/g1/concurrentMarkThread.inline.hpp"
98 #include "gc/parallel/pcTasks.hpp"
99 #endif // INCLUDE_ALL_GCS
100 #ifdef COMPILER1
101 #include "c1/c1_Compiler.hpp"
102 #endif
103 #ifdef COMPILER2
104 #include "opto/c2compiler.hpp"
105 #include "opto/idealGraphPrinter.hpp"
106 #endif
107 #if INCLUDE_RTM_OPT
108 #include "runtime/rtmLocking.hpp"
109 #endif
110
111 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
112
113 #ifdef DTRACE_ENABLED
114
115 // Only bother with this argument setup if dtrace is available
116
117 #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_START
118 #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_STOP
119
120 #define DTRACE_THREAD_PROBE(probe, javathread) \
121 { \
122 ResourceMark rm(this); \
123 int len = 0; \
124 const char* name = (javathread)->get_thread_name(); \
125 len = strlen(name); \
126 HOTSPOT_THREAD_PROBE_##probe(/* probe = start, stop */ \
127 (char *) name, len, \
128 java_lang_Thread::thread_id((javathread)->threadObj()), \
129 (uintptr_t) (javathread)->osthread()->thread_id(), \
130 java_lang_Thread::is_daemon((javathread)->threadObj())); \
131 }
132
133 #else // ndef DTRACE_ENABLED
134
135 #define DTRACE_THREAD_PROBE(probe, javathread)
136
137 #endif // ndef DTRACE_ENABLED
138
139
140 // Class hierarchy
141 // - Thread
142 // - VMThread
143 // - WatcherThread
144 // - ConcurrentMarkSweepThread
145 // - JavaThread
146 // - CompilerThread
147
148 // ======= Thread ========
149 // Support for forcing alignment of thread objects for biased locking
150 void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) {
151 if (UseBiasedLocking) {
152 const int alignment = markOopDesc::biased_lock_alignment;
153 size_t aligned_size = size + (alignment - sizeof(intptr_t));
154 void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC)
155 : AllocateHeap(aligned_size, flags, CURRENT_PC,
156 AllocFailStrategy::RETURN_NULL);
157 void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment);
158 assert(((uintptr_t) aligned_addr + (uintptr_t) size) <=
159 ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size),
160 "JavaThread alignment code overflowed allocated storage");
161 if (TraceBiasedLocking) {
162 if (aligned_addr != real_malloc_addr) {
163 tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT,
164 real_malloc_addr, aligned_addr);
165 }
166 }
167 ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr;
168 return aligned_addr;
169 } else {
170 return throw_excpt? AllocateHeap(size, flags, CURRENT_PC)
171 : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
172 }
173 }
174
175 void Thread::operator delete(void* p) {
176 if (UseBiasedLocking) {
177 void* real_malloc_addr = ((Thread*) p)->_real_malloc_address;
178 FreeHeap(real_malloc_addr);
179 } else {
180 FreeHeap(p);
181 }
182 }
183
184
185 // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread,
186 // JavaThread
187
188
189 Thread::Thread() {
190 // stack and get_thread
191 set_stack_base(NULL);
192 set_stack_size(0);
193 set_self_raw_id(0);
194 set_lgrp_id(-1);
195 DEBUG_ONLY(clear_suspendible_thread();)
196
197 // allocated data structures
198 set_osthread(NULL);
199 set_resource_area(new (mtThread)ResourceArea());
200 DEBUG_ONLY(_current_resource_mark = NULL;)
201 set_handle_area(new (mtThread) HandleArea(NULL));
202 set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(30, true));
203 set_active_handles(NULL);
204 set_free_handle_block(NULL);
205 set_last_handle_mark(NULL);
206
207 // This initial value ==> never claimed.
208 _oops_do_parity = 0;
209
210 // the handle mark links itself to last_handle_mark
211 new HandleMark(this);
212
213 // plain initialization
214 debug_only(_owned_locks = NULL;)
215 debug_only(_allow_allocation_count = 0;)
216 NOT_PRODUCT(_allow_safepoint_count = 0;)
217 NOT_PRODUCT(_skip_gcalot = false;)
218 _jvmti_env_iteration_count = 0;
219 set_allocated_bytes(0);
220 _vm_operation_started_count = 0;
221 _vm_operation_completed_count = 0;
222 _current_pending_monitor = NULL;
223 _current_pending_monitor_is_from_java = true;
224 _current_waiting_monitor = NULL;
225 _num_nested_signal = 0;
226 omFreeList = NULL;
227 omFreeCount = 0;
228 omFreeProvision = 32;
229 omInUseList = NULL;
230 omInUseCount = 0;
231
232 #ifdef ASSERT
233 _visited_for_critical_count = false;
234 #endif
235
236 _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true,
237 Monitor::_safepoint_check_sometimes);
238 _suspend_flags = 0;
239
240 // thread-specific hashCode stream generator state - Marsaglia shift-xor form
241 _hashStateX = os::random();
242 _hashStateY = 842502087;
243 _hashStateZ = 0x8767; // (int)(3579807591LL & 0xffff) ;
244 _hashStateW = 273326509;
245
246 _OnTrap = 0;
247 _schedctl = NULL;
248 _Stalled = 0;
249 _TypeTag = 0x2BAD;
250
251 // Many of the following fields are effectively final - immutable
252 // Note that nascent threads can't use the Native Monitor-Mutex
253 // construct until the _MutexEvent is initialized ...
254 // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents
255 // we might instead use a stack of ParkEvents that we could provision on-demand.
256 // The stack would act as a cache to avoid calls to ParkEvent::Allocate()
257 // and ::Release()
258 _ParkEvent = ParkEvent::Allocate(this);
259 _SleepEvent = ParkEvent::Allocate(this);
260 _MutexEvent = ParkEvent::Allocate(this);
261 _MuxEvent = ParkEvent::Allocate(this);
262
263 #ifdef CHECK_UNHANDLED_OOPS
264 if (CheckUnhandledOops) {
265 _unhandled_oops = new UnhandledOops(this);
266 }
267 #endif // CHECK_UNHANDLED_OOPS
268 #ifdef ASSERT
269 if (UseBiasedLocking) {
270 assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed");
271 assert(this == _real_malloc_address ||
272 this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment),
273 "bug in forced alignment of thread objects");
274 }
275 #endif // ASSERT
276 }
277
278 // Non-inlined version to be used where thread.inline.hpp shouldn't be included.
279 Thread* Thread::current_noinline() {
280 return Thread::current();
281 }
282
283 void Thread::initialize_thread_local_storage() {
284 // Note: Make sure this method only calls
285 // non-blocking operations. Otherwise, it might not work
286 // with the thread-startup/safepoint interaction.
287
288 // During Java thread startup, safepoint code should allow this
289 // method to complete because it may need to allocate memory to
290 // store information for the new thread.
291
292 // initialize structure dependent on thread local storage
293 ThreadLocalStorage::set_thread(this);
294 }
295
296 void Thread::record_stack_base_and_size() {
297 set_stack_base(os::current_stack_base());
298 set_stack_size(os::current_stack_size());
299 if (is_Java_thread()) {
300 ((JavaThread*) this)->set_stack_overflow_limit();
301 }
302 // CR 7190089: on Solaris, primordial thread's stack is adjusted
303 // in initialize_thread(). Without the adjustment, stack size is
304 // incorrect if stack is set to unlimited (ulimit -s unlimited).
305 // So far, only Solaris has real implementation of initialize_thread().
306 //
307 // set up any platform-specific state.
308 os::initialize_thread(this);
309
310 #if INCLUDE_NMT
311 // record thread's native stack, stack grows downward
312 address stack_low_addr = stack_base() - stack_size();
313 MemTracker::record_thread_stack(stack_low_addr, stack_size());
314 #endif // INCLUDE_NMT
315 }
316
317
318 Thread::~Thread() {
319 // Reclaim the objectmonitors from the omFreeList of the moribund thread.
320 ObjectSynchronizer::omFlush(this);
321
322 EVENT_THREAD_DESTRUCT(this);
323
324 // stack_base can be NULL if the thread is never started or exited before
325 // record_stack_base_and_size called. Although, we would like to ensure
326 // that all started threads do call record_stack_base_and_size(), there is
327 // not proper way to enforce that.
328 #if INCLUDE_NMT
329 if (_stack_base != NULL) {
330 address low_stack_addr = stack_base() - stack_size();
331 MemTracker::release_thread_stack(low_stack_addr, stack_size());
332 #ifdef ASSERT
333 set_stack_base(NULL);
334 #endif
335 }
336 #endif // INCLUDE_NMT
337
338 // deallocate data structures
339 delete resource_area();
340 // since the handle marks are using the handle area, we have to deallocated the root
341 // handle mark before deallocating the thread's handle area,
342 assert(last_handle_mark() != NULL, "check we have an element");
343 delete last_handle_mark();
344 assert(last_handle_mark() == NULL, "check we have reached the end");
345
346 // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads.
347 // We NULL out the fields for good hygiene.
348 ParkEvent::Release(_ParkEvent); _ParkEvent = NULL;
349 ParkEvent::Release(_SleepEvent); _SleepEvent = NULL;
350 ParkEvent::Release(_MutexEvent); _MutexEvent = NULL;
351 ParkEvent::Release(_MuxEvent); _MuxEvent = NULL;
352
353 delete handle_area();
354 delete metadata_handles();
355
356 // osthread() can be NULL, if creation of thread failed.
357 if (osthread() != NULL) os::free_thread(osthread());
358
359 delete _SR_lock;
360
361 // clear thread local storage if the Thread is deleting itself
362 if (this == Thread::current()) {
363 ThreadLocalStorage::set_thread(NULL);
364 } else {
365 // In the case where we're not the current thread, invalidate all the
366 // caches in case some code tries to get the current thread or the
367 // thread that was destroyed, and gets stale information.
368 ThreadLocalStorage::invalidate_all();
369 }
370 CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();)
371 }
372
373 // NOTE: dummy function for assertion purpose.
374 void Thread::run() {
375 ShouldNotReachHere();
376 }
377
378 #ifdef ASSERT
379 // Private method to check for dangling thread pointer
380 void check_for_dangling_thread_pointer(Thread *thread) {
381 assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(),
382 "possibility of dangling Thread pointer");
383 }
384 #endif
385
386 ThreadPriority Thread::get_priority(const Thread* const thread) {
387 ThreadPriority priority;
388 // Can return an error!
389 (void)os::get_priority(thread, priority);
390 assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found");
391 return priority;
392 }
393
394 void Thread::set_priority(Thread* thread, ThreadPriority priority) {
395 debug_only(check_for_dangling_thread_pointer(thread);)
396 // Can return an error!
397 (void)os::set_priority(thread, priority);
398 }
399
400
401 void Thread::start(Thread* thread) {
402 // Start is different from resume in that its safety is guaranteed by context or
403 // being called from a Java method synchronized on the Thread object.
404 if (!DisableStartThread) {
405 if (thread->is_Java_thread()) {
406 // Initialize the thread state to RUNNABLE before starting this thread.
407 // Can not set it after the thread started because we do not know the
408 // exact thread state at that time. It could be in MONITOR_WAIT or
409 // in SLEEPING or some other state.
410 java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(),
411 java_lang_Thread::RUNNABLE);
412 }
413 os::start_thread(thread);
414 }
415 }
416
417 // Enqueue a VM_Operation to do the job for us - sometime later
418 void Thread::send_async_exception(oop java_thread, oop java_throwable) {
419 VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable);
420 VMThread::execute(vm_stop);
421 }
422
423
424 // Check if an external suspend request has completed (or has been
425 // cancelled). Returns true if the thread is externally suspended and
426 // false otherwise.
427 //
428 // The bits parameter returns information about the code path through
429 // the routine. Useful for debugging:
430 //
431 // set in is_ext_suspend_completed():
432 // 0x00000001 - routine was entered
433 // 0x00000010 - routine return false at end
434 // 0x00000100 - thread exited (return false)
435 // 0x00000200 - suspend request cancelled (return false)
436 // 0x00000400 - thread suspended (return true)
437 // 0x00001000 - thread is in a suspend equivalent state (return true)
438 // 0x00002000 - thread is native and walkable (return true)
439 // 0x00004000 - thread is native_trans and walkable (needed retry)
440 //
441 // set in wait_for_ext_suspend_completion():
442 // 0x00010000 - routine was entered
443 // 0x00020000 - suspend request cancelled before loop (return false)
444 // 0x00040000 - thread suspended before loop (return true)
445 // 0x00080000 - suspend request cancelled in loop (return false)
446 // 0x00100000 - thread suspended in loop (return true)
447 // 0x00200000 - suspend not completed during retry loop (return false)
448
449 // Helper class for tracing suspend wait debug bits.
450 //
451 // 0x00000100 indicates that the target thread exited before it could
452 // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and
453 // 0x00080000 each indicate a cancelled suspend request so they don't
454 // count as wait failures either.
455 #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000)
456
457 class TraceSuspendDebugBits : public StackObj {
458 private:
459 JavaThread * jt;
460 bool is_wait;
461 bool called_by_wait; // meaningful when !is_wait
462 uint32_t * bits;
463
464 public:
465 TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait,
466 uint32_t *_bits) {
467 jt = _jt;
468 is_wait = _is_wait;
469 called_by_wait = _called_by_wait;
470 bits = _bits;
471 }
472
473 ~TraceSuspendDebugBits() {
474 if (!is_wait) {
475 #if 1
476 // By default, don't trace bits for is_ext_suspend_completed() calls.
477 // That trace is very chatty.
478 return;
479 #else
480 if (!called_by_wait) {
481 // If tracing for is_ext_suspend_completed() is enabled, then only
482 // trace calls to it from wait_for_ext_suspend_completion()
483 return;
484 }
485 #endif
486 }
487
488 if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) {
489 if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) {
490 MutexLocker ml(Threads_lock); // needed for get_thread_name()
491 ResourceMark rm;
492
493 tty->print_cr(
494 "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)",
495 jt->get_thread_name(), *bits);
496
497 guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed");
498 }
499 }
500 }
501 };
502 #undef DEBUG_FALSE_BITS
503
504
505 bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay,
506 uint32_t *bits) {
507 TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits);
508
509 bool did_trans_retry = false; // only do thread_in_native_trans retry once
510 bool do_trans_retry; // flag to force the retry
511
512 *bits |= 0x00000001;
513
514 do {
515 do_trans_retry = false;
516
517 if (is_exiting()) {
518 // Thread is in the process of exiting. This is always checked
519 // first to reduce the risk of dereferencing a freed JavaThread.
520 *bits |= 0x00000100;
521 return false;
522 }
523
524 if (!is_external_suspend()) {
525 // Suspend request is cancelled. This is always checked before
526 // is_ext_suspended() to reduce the risk of a rogue resume
527 // confusing the thread that made the suspend request.
528 *bits |= 0x00000200;
529 return false;
530 }
531
532 if (is_ext_suspended()) {
533 // thread is suspended
534 *bits |= 0x00000400;
535 return true;
536 }
537
538 // Now that we no longer do hard suspends of threads running
539 // native code, the target thread can be changing thread state
540 // while we are in this routine:
541 //
542 // _thread_in_native -> _thread_in_native_trans -> _thread_blocked
543 //
544 // We save a copy of the thread state as observed at this moment
545 // and make our decision about suspend completeness based on the
546 // copy. This closes the race where the thread state is seen as
547 // _thread_in_native_trans in the if-thread_blocked check, but is
548 // seen as _thread_blocked in if-thread_in_native_trans check.
549 JavaThreadState save_state = thread_state();
550
551 if (save_state == _thread_blocked && is_suspend_equivalent()) {
552 // If the thread's state is _thread_blocked and this blocking
553 // condition is known to be equivalent to a suspend, then we can
554 // consider the thread to be externally suspended. This means that
555 // the code that sets _thread_blocked has been modified to do
556 // self-suspension if the blocking condition releases. We also
557 // used to check for CONDVAR_WAIT here, but that is now covered by
558 // the _thread_blocked with self-suspension check.
559 //
560 // Return true since we wouldn't be here unless there was still an
561 // external suspend request.
562 *bits |= 0x00001000;
563 return true;
564 } else if (save_state == _thread_in_native && frame_anchor()->walkable()) {
565 // Threads running native code will self-suspend on native==>VM/Java
566 // transitions. If its stack is walkable (should always be the case
567 // unless this function is called before the actual java_suspend()
568 // call), then the wait is done.
569 *bits |= 0x00002000;
570 return true;
571 } else if (!called_by_wait && !did_trans_retry &&
572 save_state == _thread_in_native_trans &&
573 frame_anchor()->walkable()) {
574 // The thread is transitioning from thread_in_native to another
575 // thread state. check_safepoint_and_suspend_for_native_trans()
576 // will force the thread to self-suspend. If it hasn't gotten
577 // there yet we may have caught the thread in-between the native
578 // code check above and the self-suspend. Lucky us. If we were
579 // called by wait_for_ext_suspend_completion(), then it
580 // will be doing the retries so we don't have to.
581 //
582 // Since we use the saved thread state in the if-statement above,
583 // there is a chance that the thread has already transitioned to
584 // _thread_blocked by the time we get here. In that case, we will
585 // make a single unnecessary pass through the logic below. This
586 // doesn't hurt anything since we still do the trans retry.
587
588 *bits |= 0x00004000;
589
590 // Once the thread leaves thread_in_native_trans for another
591 // thread state, we break out of this retry loop. We shouldn't
592 // need this flag to prevent us from getting back here, but
593 // sometimes paranoia is good.
594 did_trans_retry = true;
595
596 // We wait for the thread to transition to a more usable state.
597 for (int i = 1; i <= SuspendRetryCount; i++) {
598 // We used to do an "os::yield_all(i)" call here with the intention
599 // that yielding would increase on each retry. However, the parameter
600 // is ignored on Linux which means the yield didn't scale up. Waiting
601 // on the SR_lock below provides a much more predictable scale up for
602 // the delay. It also provides a simple/direct point to check for any
603 // safepoint requests from the VMThread
604
605 // temporarily drops SR_lock while doing wait with safepoint check
606 // (if we're a JavaThread - the WatcherThread can also call this)
607 // and increase delay with each retry
608 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
609
610 // check the actual thread state instead of what we saved above
611 if (thread_state() != _thread_in_native_trans) {
612 // the thread has transitioned to another thread state so
613 // try all the checks (except this one) one more time.
614 do_trans_retry = true;
615 break;
616 }
617 } // end retry loop
618
619
620 }
621 } while (do_trans_retry);
622
623 *bits |= 0x00000010;
624 return false;
625 }
626
627 // Wait for an external suspend request to complete (or be cancelled).
628 // Returns true if the thread is externally suspended and false otherwise.
629 //
630 bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay,
631 uint32_t *bits) {
632 TraceSuspendDebugBits tsdb(this, true /* is_wait */,
633 false /* !called_by_wait */, bits);
634
635 // local flag copies to minimize SR_lock hold time
636 bool is_suspended;
637 bool pending;
638 uint32_t reset_bits;
639
640 // set a marker so is_ext_suspend_completed() knows we are the caller
641 *bits |= 0x00010000;
642
643 // We use reset_bits to reinitialize the bits value at the top of
644 // each retry loop. This allows the caller to make use of any
645 // unused bits for their own marking purposes.
646 reset_bits = *bits;
647
648 {
649 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
650 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
651 delay, bits);
652 pending = is_external_suspend();
653 }
654 // must release SR_lock to allow suspension to complete
655
656 if (!pending) {
657 // A cancelled suspend request is the only false return from
658 // is_ext_suspend_completed() that keeps us from entering the
659 // retry loop.
660 *bits |= 0x00020000;
661 return false;
662 }
663
664 if (is_suspended) {
665 *bits |= 0x00040000;
666 return true;
667 }
668
669 for (int i = 1; i <= retries; i++) {
670 *bits = reset_bits; // reinit to only track last retry
671
672 // We used to do an "os::yield_all(i)" call here with the intention
673 // that yielding would increase on each retry. However, the parameter
674 // is ignored on Linux which means the yield didn't scale up. Waiting
675 // on the SR_lock below provides a much more predictable scale up for
676 // the delay. It also provides a simple/direct point to check for any
677 // safepoint requests from the VMThread
678
679 {
680 MutexLocker ml(SR_lock());
681 // wait with safepoint check (if we're a JavaThread - the WatcherThread
682 // can also call this) and increase delay with each retry
683 SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay);
684
685 is_suspended = is_ext_suspend_completed(true /* called_by_wait */,
686 delay, bits);
687
688 // It is possible for the external suspend request to be cancelled
689 // (by a resume) before the actual suspend operation is completed.
690 // Refresh our local copy to see if we still need to wait.
691 pending = is_external_suspend();
692 }
693
694 if (!pending) {
695 // A cancelled suspend request is the only false return from
696 // is_ext_suspend_completed() that keeps us from staying in the
697 // retry loop.
698 *bits |= 0x00080000;
699 return false;
700 }
701
702 if (is_suspended) {
703 *bits |= 0x00100000;
704 return true;
705 }
706 } // end retry loop
707
708 // thread did not suspend after all our retries
709 *bits |= 0x00200000;
710 return false;
711 }
712
713 #ifndef PRODUCT
714 void JavaThread::record_jump(address target, address instr, const char* file,
715 int line) {
716
717 // This should not need to be atomic as the only way for simultaneous
718 // updates is via interrupts. Even then this should be rare or non-existent
719 // and we don't care that much anyway.
720
721 int index = _jmp_ring_index;
722 _jmp_ring_index = (index + 1) & (jump_ring_buffer_size - 1);
723 _jmp_ring[index]._target = (intptr_t) target;
724 _jmp_ring[index]._instruction = (intptr_t) instr;
725 _jmp_ring[index]._file = file;
726 _jmp_ring[index]._line = line;
727 }
728 #endif // PRODUCT
729
730 // Called by flat profiler
731 // Callers have already called wait_for_ext_suspend_completion
732 // The assertion for that is currently too complex to put here:
733 bool JavaThread::profile_last_Java_frame(frame* _fr) {
734 bool gotframe = false;
735 // self suspension saves needed state.
736 if (has_last_Java_frame() && _anchor.walkable()) {
737 *_fr = pd_last_frame();
738 gotframe = true;
739 }
740 return gotframe;
741 }
742
743 void Thread::interrupt(Thread* thread) {
744 debug_only(check_for_dangling_thread_pointer(thread);)
745 os::interrupt(thread);
746 }
747
748 bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) {
749 debug_only(check_for_dangling_thread_pointer(thread);)
750 // Note: If clear_interrupted==false, this simply fetches and
751 // returns the value of the field osthread()->interrupted().
752 return os::is_interrupted(thread, clear_interrupted);
753 }
754
755
756 // GC Support
757 bool Thread::claim_oops_do_par_case(int strong_roots_parity) {
758 jint thread_parity = _oops_do_parity;
759 if (thread_parity != strong_roots_parity) {
760 jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity);
761 if (res == thread_parity) {
762 return true;
763 } else {
764 guarantee(res == strong_roots_parity, "Or else what?");
765 return false;
766 }
767 }
768 return false;
769 }
770
771 void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
772 active_handles()->oops_do(f);
773 // Do oop for ThreadShadow
774 f->do_oop((oop*)&_pending_exception);
775 handle_area()->oops_do(f);
776 }
777
778 void Thread::nmethods_do(CodeBlobClosure* cf) {
779 // no nmethods in a generic thread...
780 }
781
782 void Thread::metadata_handles_do(void f(Metadata*)) {
783 // Only walk the Handles in Thread.
784 if (metadata_handles() != NULL) {
785 for (int i = 0; i< metadata_handles()->length(); i++) {
786 f(metadata_handles()->at(i));
787 }
788 }
789 }
790
791 void Thread::print_on(outputStream* st) const {
792 // get_priority assumes osthread initialized
793 if (osthread() != NULL) {
794 int os_prio;
795 if (os::get_native_priority(this, &os_prio) == OS_OK) {
796 st->print("os_prio=%d ", os_prio);
797 }
798 st->print("tid=" INTPTR_FORMAT " ", this);
799 ext().print_on(st);
800 osthread()->print_on(st);
801 }
802 debug_only(if (WizardMode) print_owned_locks_on(st);)
803 }
804
805 // Thread::print_on_error() is called by fatal error handler. Don't use
806 // any lock or allocate memory.
807 void Thread::print_on_error(outputStream* st, char* buf, int buflen) const {
808 if (is_VM_thread()) st->print("VMThread");
809 else if (is_Compiler_thread()) st->print("CompilerThread");
810 else if (is_Java_thread()) st->print("JavaThread");
811 else if (is_GC_task_thread()) st->print("GCTaskThread");
812 else if (is_Watcher_thread()) st->print("WatcherThread");
813 else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread");
814 else st->print("Thread");
815
816 st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]",
817 _stack_base - _stack_size, _stack_base);
818
819 if (osthread()) {
820 st->print(" [id=%d]", osthread()->thread_id());
821 }
822 }
823
824 #ifdef ASSERT
825 void Thread::print_owned_locks_on(outputStream* st) const {
826 Monitor *cur = _owned_locks;
827 if (cur == NULL) {
828 st->print(" (no locks) ");
829 } else {
830 st->print_cr(" Locks owned:");
831 while (cur) {
832 cur->print_on(st);
833 cur = cur->next();
834 }
835 }
836 }
837
838 static int ref_use_count = 0;
839
840 bool Thread::owns_locks_but_compiled_lock() const {
841 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
842 if (cur != Compile_lock) return true;
843 }
844 return false;
845 }
846
847
848 #endif
849
850 #ifndef PRODUCT
851
852 // The flag: potential_vm_operation notifies if this particular safepoint state could potential
853 // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that
854 // no threads which allow_vm_block's are held
855 void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) {
856 // Check if current thread is allowed to block at a safepoint
857 if (!(_allow_safepoint_count == 0)) {
858 fatal("Possible safepoint reached by thread that does not allow it");
859 }
860 if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) {
861 fatal("LEAF method calling lock?");
862 }
863
864 #ifdef ASSERT
865 if (potential_vm_operation && is_Java_thread()
866 && !Universe::is_bootstrapping()) {
867 // Make sure we do not hold any locks that the VM thread also uses.
868 // This could potentially lead to deadlocks
869 for (Monitor *cur = _owned_locks; cur; cur = cur->next()) {
870 // Threads_lock is special, since the safepoint synchronization will not start before this is
871 // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock,
872 // since it is used to transfer control between JavaThreads and the VMThread
873 // Do not *exclude* any locks unless you are absolutely sure it is correct. Ask someone else first!
874 if ((cur->allow_vm_block() &&
875 cur != Threads_lock &&
876 cur != Compile_lock && // Temporary: should not be necessary when we get separate compilation
877 cur != VMOperationRequest_lock &&
878 cur != VMOperationQueue_lock) ||
879 cur->rank() == Mutex::special) {
880 fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name()));
881 }
882 }
883 }
884
885 if (GCALotAtAllSafepoints) {
886 // We could enter a safepoint here and thus have a gc
887 InterfaceSupport::check_gc_alot();
888 }
889 #endif
890 }
891 #endif
892
893 bool Thread::is_in_stack(address adr) const {
894 assert(Thread::current() == this, "is_in_stack can only be called from current thread");
895 address end = os::current_stack_pointer();
896 // Allow non Java threads to call this without stack_base
897 if (_stack_base == NULL) return true;
898 if (stack_base() >= adr && adr >= end) return true;
899
900 return false;
901 }
902
903
904 bool Thread::is_in_usable_stack(address adr) const {
905 size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0;
906 size_t usable_stack_size = _stack_size - stack_guard_size;
907
908 return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size));
909 }
910
911
912 // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter
913 // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being
914 // used for compilation in the future. If that change is made, the need for these methods
915 // should be revisited, and they should be removed if possible.
916
917 bool Thread::is_lock_owned(address adr) const {
918 return on_local_stack(adr);
919 }
920
921 bool Thread::set_as_starting_thread() {
922 // NOTE: this must be called inside the main thread.
923 return os::create_main_thread((JavaThread*)this);
924 }
925
926 static void initialize_class(Symbol* class_name, TRAPS) {
927 Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK);
928 InstanceKlass::cast(klass)->initialize(CHECK);
929 }
930
931
932 // Creates the initial ThreadGroup
933 static Handle create_initial_thread_group(TRAPS) {
934 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH);
935 instanceKlassHandle klass (THREAD, k);
936
937 Handle system_instance = klass->allocate_instance_handle(CHECK_NH);
938 {
939 JavaValue result(T_VOID);
940 JavaCalls::call_special(&result,
941 system_instance,
942 klass,
943 vmSymbols::object_initializer_name(),
944 vmSymbols::void_method_signature(),
945 CHECK_NH);
946 }
947 Universe::set_system_thread_group(system_instance());
948
949 Handle main_instance = klass->allocate_instance_handle(CHECK_NH);
950 {
951 JavaValue result(T_VOID);
952 Handle string = java_lang_String::create_from_str("main", CHECK_NH);
953 JavaCalls::call_special(&result,
954 main_instance,
955 klass,
956 vmSymbols::object_initializer_name(),
957 vmSymbols::threadgroup_string_void_signature(),
958 system_instance,
959 string,
960 CHECK_NH);
961 }
962 return main_instance;
963 }
964
965 // Creates the initial Thread
966 static oop create_initial_thread(Handle thread_group, JavaThread* thread,
967 TRAPS) {
968 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL);
969 instanceKlassHandle klass (THREAD, k);
970 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL);
971
972 java_lang_Thread::set_thread(thread_oop(), thread);
973 java_lang_Thread::set_priority(thread_oop(), NormPriority);
974 thread->set_threadObj(thread_oop());
975
976 Handle string = java_lang_String::create_from_str("main", CHECK_NULL);
977
978 JavaValue result(T_VOID);
979 JavaCalls::call_special(&result, thread_oop,
980 klass,
981 vmSymbols::object_initializer_name(),
982 vmSymbols::threadgroup_string_void_signature(),
983 thread_group,
984 string,
985 CHECK_NULL);
986 return thread_oop();
987 }
988
989 static void call_initializeSystemClass(TRAPS) {
990 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
991 instanceKlassHandle klass (THREAD, k);
992
993 JavaValue result(T_VOID);
994 JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(),
995 vmSymbols::void_method_signature(), CHECK);
996 }
997
998 char java_runtime_name[128] = "";
999 char java_runtime_version[128] = "";
1000
1001 // extract the JRE name from sun.misc.Version.java_runtime_name
1002 static const char* get_java_runtime_name(TRAPS) {
1003 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1004 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1005 fieldDescriptor fd;
1006 bool found = k != NULL &&
1007 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(),
1008 vmSymbols::string_signature(), &fd);
1009 if (found) {
1010 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1011 if (name_oop == NULL) {
1012 return NULL;
1013 }
1014 const char* name = java_lang_String::as_utf8_string(name_oop,
1015 java_runtime_name,
1016 sizeof(java_runtime_name));
1017 return name;
1018 } else {
1019 return NULL;
1020 }
1021 }
1022
1023 // extract the JRE version from sun.misc.Version.java_runtime_version
1024 static const char* get_java_runtime_version(TRAPS) {
1025 Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(),
1026 Handle(), Handle(), CHECK_AND_CLEAR_NULL);
1027 fieldDescriptor fd;
1028 bool found = k != NULL &&
1029 InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(),
1030 vmSymbols::string_signature(), &fd);
1031 if (found) {
1032 oop name_oop = k->java_mirror()->obj_field(fd.offset());
1033 if (name_oop == NULL) {
1034 return NULL;
1035 }
1036 const char* name = java_lang_String::as_utf8_string(name_oop,
1037 java_runtime_version,
1038 sizeof(java_runtime_version));
1039 return name;
1040 } else {
1041 return NULL;
1042 }
1043 }
1044
1045 // General purpose hook into Java code, run once when the VM is initialized.
1046 // The Java library method itself may be changed independently from the VM.
1047 static void call_postVMInitHook(TRAPS) {
1048 Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD);
1049 instanceKlassHandle klass (THREAD, k);
1050 if (klass.not_null()) {
1051 JavaValue result(T_VOID);
1052 JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(),
1053 vmSymbols::void_method_signature(),
1054 CHECK);
1055 }
1056 }
1057
1058 static void reset_vm_info_property(TRAPS) {
1059 // the vm info string
1060 ResourceMark rm(THREAD);
1061 const char *vm_info = VM_Version::vm_info_string();
1062
1063 // java.lang.System class
1064 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK);
1065 instanceKlassHandle klass (THREAD, k);
1066
1067 // setProperty arguments
1068 Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK);
1069 Handle value_str = java_lang_String::create_from_str(vm_info, CHECK);
1070
1071 // return value
1072 JavaValue r(T_OBJECT);
1073
1074 // public static String setProperty(String key, String value);
1075 JavaCalls::call_static(&r,
1076 klass,
1077 vmSymbols::setProperty_name(),
1078 vmSymbols::string_string_string_signature(),
1079 key_str,
1080 value_str,
1081 CHECK);
1082 }
1083
1084
1085 void JavaThread::allocate_threadObj(Handle thread_group, const char* thread_name,
1086 bool daemon, TRAPS) {
1087 assert(thread_group.not_null(), "thread group should be specified");
1088 assert(threadObj() == NULL, "should only create Java thread object once");
1089
1090 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK);
1091 instanceKlassHandle klass (THREAD, k);
1092 instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
1093
1094 java_lang_Thread::set_thread(thread_oop(), this);
1095 java_lang_Thread::set_priority(thread_oop(), NormPriority);
1096 set_threadObj(thread_oop());
1097
1098 JavaValue result(T_VOID);
1099 if (thread_name != NULL) {
1100 Handle name = java_lang_String::create_from_str(thread_name, CHECK);
1101 // Thread gets assigned specified name and null target
1102 JavaCalls::call_special(&result,
1103 thread_oop,
1104 klass,
1105 vmSymbols::object_initializer_name(),
1106 vmSymbols::threadgroup_string_void_signature(),
1107 thread_group, // Argument 1
1108 name, // Argument 2
1109 THREAD);
1110 } else {
1111 // Thread gets assigned name "Thread-nnn" and null target
1112 // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument)
1113 JavaCalls::call_special(&result,
1114 thread_oop,
1115 klass,
1116 vmSymbols::object_initializer_name(),
1117 vmSymbols::threadgroup_runnable_void_signature(),
1118 thread_group, // Argument 1
1119 Handle(), // Argument 2
1120 THREAD);
1121 }
1122
1123
1124 if (daemon) {
1125 java_lang_Thread::set_daemon(thread_oop());
1126 }
1127
1128 if (HAS_PENDING_EXCEPTION) {
1129 return;
1130 }
1131
1132 KlassHandle group(THREAD, SystemDictionary::ThreadGroup_klass());
1133 Handle threadObj(THREAD, this->threadObj());
1134
1135 JavaCalls::call_special(&result,
1136 thread_group,
1137 group,
1138 vmSymbols::add_method_name(),
1139 vmSymbols::thread_void_signature(),
1140 threadObj, // Arg 1
1141 THREAD);
1142 }
1143
1144 // NamedThread -- non-JavaThread subclasses with multiple
1145 // uniquely named instances should derive from this.
1146 NamedThread::NamedThread() : Thread() {
1147 _name = NULL;
1148 _processed_thread = NULL;
1149 }
1150
1151 NamedThread::~NamedThread() {
1152 if (_name != NULL) {
1153 FREE_C_HEAP_ARRAY(char, _name);
1154 _name = NULL;
1155 }
1156 }
1157
1158 void NamedThread::set_name(const char* format, ...) {
1159 guarantee(_name == NULL, "Only get to set name once.");
1160 _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread);
1161 guarantee(_name != NULL, "alloc failure");
1162 va_list ap;
1163 va_start(ap, format);
1164 jio_vsnprintf(_name, max_name_len, format, ap);
1165 va_end(ap);
1166 }
1167
1168 void NamedThread::initialize_named_thread() {
1169 set_native_thread_name(name());
1170 }
1171
1172 void NamedThread::print_on(outputStream* st) const {
1173 st->print("\"%s\" ", name());
1174 Thread::print_on(st);
1175 st->cr();
1176 }
1177
1178
1179 // ======= WatcherThread ========
1180
1181 // The watcher thread exists to simulate timer interrupts. It should
1182 // be replaced by an abstraction over whatever native support for
1183 // timer interrupts exists on the platform.
1184
1185 WatcherThread* WatcherThread::_watcher_thread = NULL;
1186 bool WatcherThread::_startable = false;
1187 volatile bool WatcherThread::_should_terminate = false;
1188
1189 WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) {
1190 assert(watcher_thread() == NULL, "we can only allocate one WatcherThread");
1191 if (os::create_thread(this, os::watcher_thread)) {
1192 _watcher_thread = this;
1193
1194 // Set the watcher thread to the highest OS priority which should not be
1195 // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY
1196 // is created. The only normal thread using this priority is the reference
1197 // handler thread, which runs for very short intervals only.
1198 // If the VMThread's priority is not lower than the WatcherThread profiling
1199 // will be inaccurate.
1200 os::set_priority(this, MaxPriority);
1201 if (!DisableStartThread) {
1202 os::start_thread(this);
1203 }
1204 }
1205 }
1206
1207 int WatcherThread::sleep() const {
1208 // The WatcherThread does not participate in the safepoint protocol
1209 // for the PeriodicTask_lock because it is not a JavaThread.
1210 MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag);
1211
1212 if (_should_terminate) {
1213 // check for termination before we do any housekeeping or wait
1214 return 0; // we did not sleep.
1215 }
1216
1217 // remaining will be zero if there are no tasks,
1218 // causing the WatcherThread to sleep until a task is
1219 // enrolled
1220 int remaining = PeriodicTask::time_to_wait();
1221 int time_slept = 0;
1222
1223 // we expect this to timeout - we only ever get unparked when
1224 // we should terminate or when a new task has been enrolled
1225 OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */);
1226
1227 jlong time_before_loop = os::javaTimeNanos();
1228
1229 while (true) {
1230 bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag,
1231 remaining);
1232 jlong now = os::javaTimeNanos();
1233
1234 if (remaining == 0) {
1235 // if we didn't have any tasks we could have waited for a long time
1236 // consider the time_slept zero and reset time_before_loop
1237 time_slept = 0;
1238 time_before_loop = now;
1239 } else {
1240 // need to recalculate since we might have new tasks in _tasks
1241 time_slept = (int) ((now - time_before_loop) / 1000000);
1242 }
1243
1244 // Change to task list or spurious wakeup of some kind
1245 if (timedout || _should_terminate) {
1246 break;
1247 }
1248
1249 remaining = PeriodicTask::time_to_wait();
1250 if (remaining == 0) {
1251 // Last task was just disenrolled so loop around and wait until
1252 // another task gets enrolled
1253 continue;
1254 }
1255
1256 remaining -= time_slept;
1257 if (remaining <= 0) {
1258 break;
1259 }
1260 }
1261
1262 return time_slept;
1263 }
1264
1265 void WatcherThread::run() {
1266 assert(this == watcher_thread(), "just checking");
1267
1268 this->record_stack_base_and_size();
1269 this->initialize_thread_local_storage();
1270 this->set_native_thread_name(this->name());
1271 this->set_active_handles(JNIHandleBlock::allocate_block());
1272 while (true) {
1273 assert(watcher_thread() == Thread::current(), "thread consistency check");
1274 assert(watcher_thread() == this, "thread consistency check");
1275
1276 // Calculate how long it'll be until the next PeriodicTask work
1277 // should be done, and sleep that amount of time.
1278 int time_waited = sleep();
1279
1280 if (is_error_reported()) {
1281 // A fatal error has happened, the error handler(VMError::report_and_die)
1282 // should abort JVM after creating an error log file. However in some
1283 // rare cases, the error handler itself might deadlock. Here we try to
1284 // kill JVM if the fatal error handler fails to abort in 2 minutes.
1285 //
1286 // This code is in WatcherThread because WatcherThread wakes up
1287 // periodically so the fatal error handler doesn't need to do anything;
1288 // also because the WatcherThread is less likely to crash than other
1289 // threads.
1290
1291 for (;;) {
1292 if (!ShowMessageBoxOnError
1293 && (OnError == NULL || OnError[0] == '\0')
1294 && Arguments::abort_hook() == NULL) {
1295 os::sleep(this, ErrorLogTimeout * 60 * 1000, false);
1296 fdStream err(defaultStream::output_fd());
1297 err.print_raw_cr("# [ timer expired, abort... ]");
1298 // skip atexit/vm_exit/vm_abort hooks
1299 os::die();
1300 }
1301
1302 // Wake up 5 seconds later, the fatal handler may reset OnError or
1303 // ShowMessageBoxOnError when it is ready to abort.
1304 os::sleep(this, 5 * 1000, false);
1305 }
1306 }
1307
1308 if (_should_terminate) {
1309 // check for termination before posting the next tick
1310 break;
1311 }
1312
1313 PeriodicTask::real_time_tick(time_waited);
1314 }
1315
1316 // Signal that it is terminated
1317 {
1318 MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag);
1319 _watcher_thread = NULL;
1320 Terminator_lock->notify();
1321 }
1322
1323 // Thread destructor usually does this..
1324 ThreadLocalStorage::set_thread(NULL);
1325 }
1326
1327 void WatcherThread::start() {
1328 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1329
1330 if (watcher_thread() == NULL && _startable) {
1331 _should_terminate = false;
1332 // Create the single instance of WatcherThread
1333 new WatcherThread();
1334 }
1335 }
1336
1337 void WatcherThread::make_startable() {
1338 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1339 _startable = true;
1340 }
1341
1342 void WatcherThread::stop() {
1343 {
1344 // Follow normal safepoint aware lock enter protocol since the
1345 // WatcherThread is stopped by another JavaThread.
1346 MutexLocker ml(PeriodicTask_lock);
1347 _should_terminate = true;
1348
1349 WatcherThread* watcher = watcher_thread();
1350 if (watcher != NULL) {
1351 // unpark the WatcherThread so it can see that it should terminate
1352 watcher->unpark();
1353 }
1354 }
1355
1356 MutexLocker mu(Terminator_lock);
1357
1358 while (watcher_thread() != NULL) {
1359 // This wait should make safepoint checks, wait without a timeout,
1360 // and wait as a suspend-equivalent condition.
1361 //
1362 // Note: If the FlatProfiler is running, then this thread is waiting
1363 // for the WatcherThread to terminate and the WatcherThread, via the
1364 // FlatProfiler task, is waiting for the external suspend request on
1365 // this thread to complete. wait_for_ext_suspend_completion() will
1366 // eventually timeout, but that takes time. Making this wait a
1367 // suspend-equivalent condition solves that timeout problem.
1368 //
1369 Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
1370 Mutex::_as_suspend_equivalent_flag);
1371 }
1372 }
1373
1374 void WatcherThread::unpark() {
1375 assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required");
1376 PeriodicTask_lock->notify();
1377 }
1378
1379 void WatcherThread::print_on(outputStream* st) const {
1380 st->print("\"%s\" ", name());
1381 Thread::print_on(st);
1382 st->cr();
1383 }
1384
1385 // ======= JavaThread ========
1386
1387 // A JavaThread is a normal Java thread
1388
1389 void JavaThread::initialize() {
1390 // Initialize fields
1391
1392 // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids)
1393 set_claimed_par_id(UINT_MAX);
1394
1395 set_saved_exception_pc(NULL);
1396 set_threadObj(NULL);
1397 _anchor.clear();
1398 set_entry_point(NULL);
1399 set_jni_functions(jni_functions());
1400 set_callee_target(NULL);
1401 set_vm_result(NULL);
1402 set_vm_result_2(NULL);
1403 set_vframe_array_head(NULL);
1404 set_vframe_array_last(NULL);
1405 set_deferred_locals(NULL);
1406 set_deopt_mark(NULL);
1407 set_deopt_nmethod(NULL);
1408 clear_must_deopt_id();
1409 set_monitor_chunks(NULL);
1410 set_next(NULL);
1411 set_thread_state(_thread_new);
1412 _terminated = _not_terminated;
1413 _privileged_stack_top = NULL;
1414 _array_for_gc = NULL;
1415 _suspend_equivalent = false;
1416 _in_deopt_handler = 0;
1417 _doing_unsafe_access = false;
1418 _stack_guard_state = stack_guard_unused;
1419 (void)const_cast<oop&>(_exception_oop = oop(NULL));
1420 _exception_pc = 0;
1421 _exception_handler_pc = 0;
1422 _is_method_handle_return = 0;
1423 _jvmti_thread_state= NULL;
1424 _should_post_on_exceptions_flag = JNI_FALSE;
1425 _jvmti_get_loaded_classes_closure = NULL;
1426 _interp_only_mode = 0;
1427 _special_runtime_exit_condition = _no_async_condition;
1428 _pending_async_exception = NULL;
1429 _thread_stat = NULL;
1430 _thread_stat = new ThreadStatistics();
1431 _blocked_on_compilation = false;
1432 _jni_active_critical = 0;
1433 _pending_jni_exception_check_fn = NULL;
1434 _do_not_unlock_if_synchronized = false;
1435 _cached_monitor_info = NULL;
1436 _parker = Parker::Allocate(this);
1437
1438 #ifndef PRODUCT
1439 _jmp_ring_index = 0;
1440 for (int ji = 0; ji < jump_ring_buffer_size; ji++) {
1441 record_jump(NULL, NULL, NULL, 0);
1442 }
1443 #endif // PRODUCT
1444
1445 set_thread_profiler(NULL);
1446 if (FlatProfiler::is_active()) {
1447 // This is where we would decide to either give each thread it's own profiler
1448 // or use one global one from FlatProfiler,
1449 // or up to some count of the number of profiled threads, etc.
1450 ThreadProfiler* pp = new ThreadProfiler();
1451 pp->engage();
1452 set_thread_profiler(pp);
1453 }
1454
1455 // Setup safepoint state info for this thread
1456 ThreadSafepointState::create(this);
1457
1458 debug_only(_java_call_counter = 0);
1459
1460 // JVMTI PopFrame support
1461 _popframe_condition = popframe_inactive;
1462 _popframe_preserved_args = NULL;
1463 _popframe_preserved_args_size = 0;
1464 _frames_to_pop_failed_realloc = 0;
1465
1466 pd_initialize();
1467 }
1468
1469 #if INCLUDE_ALL_GCS
1470 SATBMarkQueueSet JavaThread::_satb_mark_queue_set;
1471 DirtyCardQueueSet JavaThread::_dirty_card_queue_set;
1472 #endif // INCLUDE_ALL_GCS
1473
1474 JavaThread::JavaThread(bool is_attaching_via_jni) :
1475 Thread()
1476 #if INCLUDE_ALL_GCS
1477 , _satb_mark_queue(&_satb_mark_queue_set),
1478 _dirty_card_queue(&_dirty_card_queue_set)
1479 #endif // INCLUDE_ALL_GCS
1480 {
1481 initialize();
1482 if (is_attaching_via_jni) {
1483 _jni_attach_state = _attaching_via_jni;
1484 } else {
1485 _jni_attach_state = _not_attaching_via_jni;
1486 }
1487 assert(deferred_card_mark().is_empty(), "Default MemRegion ctor");
1488 }
1489
1490 bool JavaThread::reguard_stack(address cur_sp) {
1491 if (_stack_guard_state != stack_guard_yellow_disabled) {
1492 return true; // Stack already guarded or guard pages not needed.
1493 }
1494
1495 if (register_stack_overflow()) {
1496 // For those architectures which have separate register and
1497 // memory stacks, we must check the register stack to see if
1498 // it has overflowed.
1499 return false;
1500 }
1501
1502 // Java code never executes within the yellow zone: the latter is only
1503 // there to provoke an exception during stack banging. If java code
1504 // is executing there, either StackShadowPages should be larger, or
1505 // some exception code in c1, c2 or the interpreter isn't unwinding
1506 // when it should.
1507 guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages");
1508
1509 enable_stack_yellow_zone();
1510 return true;
1511 }
1512
1513 bool JavaThread::reguard_stack(void) {
1514 return reguard_stack(os::current_stack_pointer());
1515 }
1516
1517
1518 void JavaThread::block_if_vm_exited() {
1519 if (_terminated == _vm_exited) {
1520 // _vm_exited is set at safepoint, and Threads_lock is never released
1521 // we will block here forever
1522 Threads_lock->lock_without_safepoint_check();
1523 ShouldNotReachHere();
1524 }
1525 }
1526
1527
1528 // Remove this ifdef when C1 is ported to the compiler interface.
1529 static void compiler_thread_entry(JavaThread* thread, TRAPS);
1530 static void sweeper_thread_entry(JavaThread* thread, TRAPS);
1531
1532 JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) :
1533 Thread()
1534 #if INCLUDE_ALL_GCS
1535 , _satb_mark_queue(&_satb_mark_queue_set),
1536 _dirty_card_queue(&_dirty_card_queue_set)
1537 #endif // INCLUDE_ALL_GCS
1538 {
1539 initialize();
1540 _jni_attach_state = _not_attaching_via_jni;
1541 set_entry_point(entry_point);
1542 // Create the native thread itself.
1543 // %note runtime_23
1544 os::ThreadType thr_type = os::java_thread;
1545 thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread :
1546 os::java_thread;
1547 os::create_thread(this, thr_type, stack_sz);
1548 // The _osthread may be NULL here because we ran out of memory (too many threads active).
1549 // We need to throw and OutOfMemoryError - however we cannot do this here because the caller
1550 // may hold a lock and all locks must be unlocked before throwing the exception (throwing
1551 // the exception consists of creating the exception object & initializing it, initialization
1552 // will leave the VM via a JavaCall and then all locks must be unlocked).
1553 //
1554 // The thread is still suspended when we reach here. Thread must be explicit started
1555 // by creator! Furthermore, the thread must also explicitly be added to the Threads list
1556 // by calling Threads:add. The reason why this is not done here, is because the thread
1557 // object must be fully initialized (take a look at JVM_Start)
1558 }
1559
1560 JavaThread::~JavaThread() {
1561
1562 // JSR166 -- return the parker to the free list
1563 Parker::Release(_parker);
1564 _parker = NULL;
1565
1566 // Free any remaining previous UnrollBlock
1567 vframeArray* old_array = vframe_array_last();
1568
1569 if (old_array != NULL) {
1570 Deoptimization::UnrollBlock* old_info = old_array->unroll_block();
1571 old_array->set_unroll_block(NULL);
1572 delete old_info;
1573 delete old_array;
1574 }
1575
1576 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred = deferred_locals();
1577 if (deferred != NULL) {
1578 // This can only happen if thread is destroyed before deoptimization occurs.
1579 assert(deferred->length() != 0, "empty array!");
1580 do {
1581 jvmtiDeferredLocalVariableSet* dlv = deferred->at(0);
1582 deferred->remove_at(0);
1583 // individual jvmtiDeferredLocalVariableSet are CHeapObj's
1584 delete dlv;
1585 } while (deferred->length() != 0);
1586 delete deferred;
1587 }
1588
1589 // All Java related clean up happens in exit
1590 ThreadSafepointState::destroy(this);
1591 if (_thread_profiler != NULL) delete _thread_profiler;
1592 if (_thread_stat != NULL) delete _thread_stat;
1593 }
1594
1595
1596 // The first routine called by a new Java thread
1597 void JavaThread::run() {
1598 // initialize thread-local alloc buffer related fields
1599 this->initialize_tlab();
1600
1601 // used to test validity of stack trace backs
1602 this->record_base_of_stack_pointer();
1603
1604 // Record real stack base and size.
1605 this->record_stack_base_and_size();
1606
1607 // Initialize thread local storage; set before calling MutexLocker
1608 this->initialize_thread_local_storage();
1609
1610 this->create_stack_guard_pages();
1611
1612 this->cache_global_variables();
1613
1614 // Thread is now sufficient initialized to be handled by the safepoint code as being
1615 // in the VM. Change thread state from _thread_new to _thread_in_vm
1616 ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
1617
1618 assert(JavaThread::current() == this, "sanity check");
1619 assert(!Thread::current()->owns_locks(), "sanity check");
1620
1621 DTRACE_THREAD_PROBE(start, this);
1622
1623 // This operation might block. We call that after all safepoint checks for a new thread has
1624 // been completed.
1625 this->set_active_handles(JNIHandleBlock::allocate_block());
1626
1627 if (JvmtiExport::should_post_thread_life()) {
1628 JvmtiExport::post_thread_start(this);
1629 }
1630
1631 EventThreadStart event;
1632 if (event.should_commit()) {
1633 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1634 event.commit();
1635 }
1636
1637 // We call another function to do the rest so we are sure that the stack addresses used
1638 // from there will be lower than the stack base just computed
1639 thread_main_inner();
1640
1641 // Note, thread is no longer valid at this point!
1642 }
1643
1644
1645 void JavaThread::thread_main_inner() {
1646 assert(JavaThread::current() == this, "sanity check");
1647 assert(this->threadObj() != NULL, "just checking");
1648
1649 // Execute thread entry point unless this thread has a pending exception
1650 // or has been stopped before starting.
1651 // Note: Due to JVM_StopThread we can have pending exceptions already!
1652 if (!this->has_pending_exception() &&
1653 !java_lang_Thread::is_stillborn(this->threadObj())) {
1654 {
1655 ResourceMark rm(this);
1656 this->set_native_thread_name(this->get_thread_name());
1657 }
1658 HandleMark hm(this);
1659 this->entry_point()(this, this);
1660 }
1661
1662 DTRACE_THREAD_PROBE(stop, this);
1663
1664 this->exit(false);
1665 delete this;
1666 }
1667
1668
1669 static void ensure_join(JavaThread* thread) {
1670 // We do not need to grap the Threads_lock, since we are operating on ourself.
1671 Handle threadObj(thread, thread->threadObj());
1672 assert(threadObj.not_null(), "java thread object must exist");
1673 ObjectLocker lock(threadObj, thread);
1674 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1675 thread->clear_pending_exception();
1676 // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED.
1677 java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
1678 // Clear the native thread instance - this makes isAlive return false and allows the join()
1679 // to complete once we've done the notify_all below
1680 java_lang_Thread::set_thread(threadObj(), NULL);
1681 lock.notify_all(thread);
1682 // Ignore pending exception (ThreadDeath), since we are exiting anyway
1683 thread->clear_pending_exception();
1684 }
1685
1686
1687 // For any new cleanup additions, please check to see if they need to be applied to
1688 // cleanup_failed_attach_current_thread as well.
1689 void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
1690 assert(this == JavaThread::current(), "thread consistency check");
1691
1692 HandleMark hm(this);
1693 Handle uncaught_exception(this, this->pending_exception());
1694 this->clear_pending_exception();
1695 Handle threadObj(this, this->threadObj());
1696 assert(threadObj.not_null(), "Java thread object should be created");
1697
1698 if (get_thread_profiler() != NULL) {
1699 get_thread_profiler()->disengage();
1700 ResourceMark rm;
1701 get_thread_profiler()->print(get_thread_name());
1702 }
1703
1704
1705 // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place
1706 {
1707 EXCEPTION_MARK;
1708
1709 CLEAR_PENDING_EXCEPTION;
1710 }
1711 if (!destroy_vm) {
1712 if (uncaught_exception.not_null()) {
1713 EXCEPTION_MARK;
1714 // Call method Thread.dispatchUncaughtException().
1715 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1716 JavaValue result(T_VOID);
1717 JavaCalls::call_virtual(&result,
1718 threadObj, thread_klass,
1719 vmSymbols::dispatchUncaughtException_name(),
1720 vmSymbols::throwable_void_signature(),
1721 uncaught_exception,
1722 THREAD);
1723 if (HAS_PENDING_EXCEPTION) {
1724 ResourceMark rm(this);
1725 jio_fprintf(defaultStream::error_stream(),
1726 "\nException: %s thrown from the UncaughtExceptionHandler"
1727 " in thread \"%s\"\n",
1728 pending_exception()->klass()->external_name(),
1729 get_thread_name());
1730 CLEAR_PENDING_EXCEPTION;
1731 }
1732 }
1733
1734 // Called before the java thread exit since we want to read info
1735 // from java_lang_Thread object
1736 EventThreadEnd event;
1737 if (event.should_commit()) {
1738 event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj()));
1739 event.commit();
1740 }
1741
1742 // Call after last event on thread
1743 EVENT_THREAD_EXIT(this);
1744
1745 // Call Thread.exit(). We try 3 times in case we got another Thread.stop during
1746 // the execution of the method. If that is not enough, then we don't really care. Thread.stop
1747 // is deprecated anyhow.
1748 if (!is_Compiler_thread()) {
1749 int count = 3;
1750 while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) {
1751 EXCEPTION_MARK;
1752 JavaValue result(T_VOID);
1753 KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass());
1754 JavaCalls::call_virtual(&result,
1755 threadObj, thread_klass,
1756 vmSymbols::exit_method_name(),
1757 vmSymbols::void_method_signature(),
1758 THREAD);
1759 CLEAR_PENDING_EXCEPTION;
1760 }
1761 }
1762 // notify JVMTI
1763 if (JvmtiExport::should_post_thread_life()) {
1764 JvmtiExport::post_thread_end(this);
1765 }
1766
1767 // We have notified the agents that we are exiting, before we go on,
1768 // we must check for a pending external suspend request and honor it
1769 // in order to not surprise the thread that made the suspend request.
1770 while (true) {
1771 {
1772 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1773 if (!is_external_suspend()) {
1774 set_terminated(_thread_exiting);
1775 ThreadService::current_thread_exiting(this);
1776 break;
1777 }
1778 // Implied else:
1779 // Things get a little tricky here. We have a pending external
1780 // suspend request, but we are holding the SR_lock so we
1781 // can't just self-suspend. So we temporarily drop the lock
1782 // and then self-suspend.
1783 }
1784
1785 ThreadBlockInVM tbivm(this);
1786 java_suspend_self();
1787
1788 // We're done with this suspend request, but we have to loop around
1789 // and check again. Eventually we will get SR_lock without a pending
1790 // external suspend request and will be able to mark ourselves as
1791 // exiting.
1792 }
1793 // no more external suspends are allowed at this point
1794 } else {
1795 // before_exit() has already posted JVMTI THREAD_END events
1796 }
1797
1798 // Notify waiters on thread object. This has to be done after exit() is called
1799 // on the thread (if the thread is the last thread in a daemon ThreadGroup the
1800 // group should have the destroyed bit set before waiters are notified).
1801 ensure_join(this);
1802 assert(!this->has_pending_exception(), "ensure_join should have cleared");
1803
1804 // 6282335 JNI DetachCurrentThread spec states that all Java monitors
1805 // held by this thread must be released. A detach operation must only
1806 // get here if there are no Java frames on the stack. Therefore, any
1807 // owned monitors at this point MUST be JNI-acquired monitors which are
1808 // pre-inflated and in the monitor cache.
1809 //
1810 // ensure_join() ignores IllegalThreadStateExceptions, and so does this.
1811 if (exit_type == jni_detach && JNIDetachReleasesMonitors) {
1812 assert(!this->has_last_Java_frame(), "detaching with Java frames?");
1813 ObjectSynchronizer::release_monitors_owned_by_thread(this);
1814 assert(!this->has_pending_exception(), "release_monitors should have cleared");
1815 }
1816
1817 // These things needs to be done while we are still a Java Thread. Make sure that thread
1818 // is in a consistent state, in case GC happens
1819 assert(_privileged_stack_top == NULL, "must be NULL when we get here");
1820
1821 if (active_handles() != NULL) {
1822 JNIHandleBlock* block = active_handles();
1823 set_active_handles(NULL);
1824 JNIHandleBlock::release_block(block);
1825 }
1826
1827 if (free_handle_block() != NULL) {
1828 JNIHandleBlock* block = free_handle_block();
1829 set_free_handle_block(NULL);
1830 JNIHandleBlock::release_block(block);
1831 }
1832
1833 // These have to be removed while this is still a valid thread.
1834 remove_stack_guard_pages();
1835
1836 if (UseTLAB) {
1837 tlab().make_parsable(true); // retire TLAB
1838 }
1839
1840 if (JvmtiEnv::environments_might_exist()) {
1841 JvmtiExport::cleanup_thread(this);
1842 }
1843
1844 // We must flush any deferred card marks before removing a thread from
1845 // the list of active threads.
1846 Universe::heap()->flush_deferred_store_barrier(this);
1847 assert(deferred_card_mark().is_empty(), "Should have been flushed");
1848
1849 #if INCLUDE_ALL_GCS
1850 // We must flush the G1-related buffers before removing a thread
1851 // from the list of active threads. We must do this after any deferred
1852 // card marks have been flushed (above) so that any entries that are
1853 // added to the thread's dirty card queue as a result are not lost.
1854 if (UseG1GC) {
1855 flush_barrier_queues();
1856 }
1857 #endif // INCLUDE_ALL_GCS
1858
1859 // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread
1860 Threads::remove(this);
1861 }
1862
1863 #if INCLUDE_ALL_GCS
1864 // Flush G1-related queues.
1865 void JavaThread::flush_barrier_queues() {
1866 satb_mark_queue().flush();
1867 dirty_card_queue().flush();
1868 }
1869
1870 void JavaThread::initialize_queues() {
1871 assert(!SafepointSynchronize::is_at_safepoint(),
1872 "we should not be at a safepoint");
1873
1874 ObjPtrQueue& satb_queue = satb_mark_queue();
1875 SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set();
1876 // The SATB queue should have been constructed with its active
1877 // field set to false.
1878 assert(!satb_queue.is_active(), "SATB queue should not be active");
1879 assert(satb_queue.is_empty(), "SATB queue should be empty");
1880 // If we are creating the thread during a marking cycle, we should
1881 // set the active field of the SATB queue to true.
1882 if (satb_queue_set.is_active()) {
1883 satb_queue.set_active(true);
1884 }
1885
1886 DirtyCardQueue& dirty_queue = dirty_card_queue();
1887 // The dirty card queue should have been constructed with its
1888 // active field set to true.
1889 assert(dirty_queue.is_active(), "dirty card queue should be active");
1890 }
1891 #endif // INCLUDE_ALL_GCS
1892
1893 void JavaThread::cleanup_failed_attach_current_thread() {
1894 if (get_thread_profiler() != NULL) {
1895 get_thread_profiler()->disengage();
1896 ResourceMark rm;
1897 get_thread_profiler()->print(get_thread_name());
1898 }
1899
1900 if (active_handles() != NULL) {
1901 JNIHandleBlock* block = active_handles();
1902 set_active_handles(NULL);
1903 JNIHandleBlock::release_block(block);
1904 }
1905
1906 if (free_handle_block() != NULL) {
1907 JNIHandleBlock* block = free_handle_block();
1908 set_free_handle_block(NULL);
1909 JNIHandleBlock::release_block(block);
1910 }
1911
1912 // These have to be removed while this is still a valid thread.
1913 remove_stack_guard_pages();
1914
1915 if (UseTLAB) {
1916 tlab().make_parsable(true); // retire TLAB, if any
1917 }
1918
1919 #if INCLUDE_ALL_GCS
1920 if (UseG1GC) {
1921 flush_barrier_queues();
1922 }
1923 #endif // INCLUDE_ALL_GCS
1924
1925 Threads::remove(this);
1926 delete this;
1927 }
1928
1929
1930
1931
1932 JavaThread* JavaThread::active() {
1933 Thread* thread = ThreadLocalStorage::thread();
1934 assert(thread != NULL, "just checking");
1935 if (thread->is_Java_thread()) {
1936 return (JavaThread*) thread;
1937 } else {
1938 assert(thread->is_VM_thread(), "this must be a vm thread");
1939 VM_Operation* op = ((VMThread*) thread)->vm_operation();
1940 JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread();
1941 assert(ret->is_Java_thread(), "must be a Java thread");
1942 return ret;
1943 }
1944 }
1945
1946 bool JavaThread::is_lock_owned(address adr) const {
1947 if (Thread::is_lock_owned(adr)) return true;
1948
1949 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
1950 if (chunk->contains(adr)) return true;
1951 }
1952
1953 return false;
1954 }
1955
1956
1957 void JavaThread::add_monitor_chunk(MonitorChunk* chunk) {
1958 chunk->set_next(monitor_chunks());
1959 set_monitor_chunks(chunk);
1960 }
1961
1962 void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) {
1963 guarantee(monitor_chunks() != NULL, "must be non empty");
1964 if (monitor_chunks() == chunk) {
1965 set_monitor_chunks(chunk->next());
1966 } else {
1967 MonitorChunk* prev = monitor_chunks();
1968 while (prev->next() != chunk) prev = prev->next();
1969 prev->set_next(chunk->next());
1970 }
1971 }
1972
1973 // JVM support.
1974
1975 // Note: this function shouldn't block if it's called in
1976 // _thread_in_native_trans state (such as from
1977 // check_special_condition_for_native_trans()).
1978 void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) {
1979
1980 if (has_last_Java_frame() && has_async_condition()) {
1981 // If we are at a polling page safepoint (not a poll return)
1982 // then we must defer async exception because live registers
1983 // will be clobbered by the exception path. Poll return is
1984 // ok because the call we a returning from already collides
1985 // with exception handling registers and so there is no issue.
1986 // (The exception handling path kills call result registers but
1987 // this is ok since the exception kills the result anyway).
1988
1989 if (is_at_poll_safepoint()) {
1990 // if the code we are returning to has deoptimized we must defer
1991 // the exception otherwise live registers get clobbered on the
1992 // exception path before deoptimization is able to retrieve them.
1993 //
1994 RegisterMap map(this, false);
1995 frame caller_fr = last_frame().sender(&map);
1996 assert(caller_fr.is_compiled_frame(), "what?");
1997 if (caller_fr.is_deoptimized_frame()) {
1998 if (TraceExceptions) {
1999 ResourceMark rm;
2000 tty->print_cr("deferred async exception at compiled safepoint");
2001 }
2002 return;
2003 }
2004 }
2005 }
2006
2007 JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition();
2008 if (condition == _no_async_condition) {
2009 // Conditions have changed since has_special_runtime_exit_condition()
2010 // was called:
2011 // - if we were here only because of an external suspend request,
2012 // then that was taken care of above (or cancelled) so we are done
2013 // - if we were here because of another async request, then it has
2014 // been cleared between the has_special_runtime_exit_condition()
2015 // and now so again we are done
2016 return;
2017 }
2018
2019 // Check for pending async. exception
2020 if (_pending_async_exception != NULL) {
2021 // Only overwrite an already pending exception, if it is not a threadDeath.
2022 if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) {
2023
2024 // We cannot call Exceptions::_throw(...) here because we cannot block
2025 set_pending_exception(_pending_async_exception, __FILE__, __LINE__);
2026
2027 if (TraceExceptions) {
2028 ResourceMark rm;
2029 tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this);
2030 if (has_last_Java_frame()) {
2031 frame f = last_frame();
2032 tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp());
2033 }
2034 tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2035 }
2036 _pending_async_exception = NULL;
2037 clear_has_async_exception();
2038 }
2039 }
2040
2041 if (check_unsafe_error &&
2042 condition == _async_unsafe_access_error && !has_pending_exception()) {
2043 condition = _no_async_condition; // done
2044 switch (thread_state()) {
2045 case _thread_in_vm: {
2046 JavaThread* THREAD = this;
2047 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2048 }
2049 case _thread_in_native: {
2050 ThreadInVMfromNative tiv(this);
2051 JavaThread* THREAD = this;
2052 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation");
2053 }
2054 case _thread_in_Java: {
2055 ThreadInVMfromJava tiv(this);
2056 JavaThread* THREAD = this;
2057 THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code");
2058 }
2059 default:
2060 ShouldNotReachHere();
2061 }
2062 }
2063
2064 assert(condition == _no_async_condition || has_pending_exception() ||
2065 (!check_unsafe_error && condition == _async_unsafe_access_error),
2066 "must have handled the async condition, if no exception");
2067 }
2068
2069 void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) {
2070 //
2071 // Check for pending external suspend. Internal suspend requests do
2072 // not use handle_special_runtime_exit_condition().
2073 // If JNIEnv proxies are allowed, don't self-suspend if the target
2074 // thread is not the current thread. In older versions of jdbx, jdbx
2075 // threads could call into the VM with another thread's JNIEnv so we
2076 // can be here operating on behalf of a suspended thread (4432884).
2077 bool do_self_suspend = is_external_suspend_with_lock();
2078 if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) {
2079 //
2080 // Because thread is external suspended the safepoint code will count
2081 // thread as at a safepoint. This can be odd because we can be here
2082 // as _thread_in_Java which would normally transition to _thread_blocked
2083 // at a safepoint. We would like to mark the thread as _thread_blocked
2084 // before calling java_suspend_self like all other callers of it but
2085 // we must then observe proper safepoint protocol. (We can't leave
2086 // _thread_blocked with a safepoint in progress). However we can be
2087 // here as _thread_in_native_trans so we can't use a normal transition
2088 // constructor/destructor pair because they assert on that type of
2089 // transition. We could do something like:
2090 //
2091 // JavaThreadState state = thread_state();
2092 // set_thread_state(_thread_in_vm);
2093 // {
2094 // ThreadBlockInVM tbivm(this);
2095 // java_suspend_self()
2096 // }
2097 // set_thread_state(_thread_in_vm_trans);
2098 // if (safepoint) block;
2099 // set_thread_state(state);
2100 //
2101 // but that is pretty messy. Instead we just go with the way the
2102 // code has worked before and note that this is the only path to
2103 // java_suspend_self that doesn't put the thread in _thread_blocked
2104 // mode.
2105
2106 frame_anchor()->make_walkable(this);
2107 java_suspend_self();
2108
2109 // We might be here for reasons in addition to the self-suspend request
2110 // so check for other async requests.
2111 }
2112
2113 if (check_asyncs) {
2114 check_and_handle_async_exceptions();
2115 }
2116 }
2117
2118 void JavaThread::send_thread_stop(oop java_throwable) {
2119 assert(Thread::current()->is_VM_thread(), "should be in the vm thread");
2120 assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code");
2121 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
2122
2123 // Do not throw asynchronous exceptions against the compiler thread
2124 // (the compiler thread should not be a Java thread -- fix in 1.4.2)
2125 if (is_Compiler_thread()) return;
2126
2127 {
2128 // Actually throw the Throwable against the target Thread - however
2129 // only if there is no thread death exception installed already.
2130 if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) {
2131 // If the topmost frame is a runtime stub, then we are calling into
2132 // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..)
2133 // must deoptimize the caller before continuing, as the compiled exception handler table
2134 // may not be valid
2135 if (has_last_Java_frame()) {
2136 frame f = last_frame();
2137 if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) {
2138 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2139 RegisterMap reg_map(this, UseBiasedLocking);
2140 frame compiled_frame = f.sender(®_map);
2141 if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) {
2142 Deoptimization::deoptimize(this, compiled_frame, ®_map);
2143 }
2144 }
2145 }
2146
2147 // Set async. pending exception in thread.
2148 set_pending_async_exception(java_throwable);
2149
2150 if (TraceExceptions) {
2151 ResourceMark rm;
2152 tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name());
2153 }
2154 // for AbortVMOnException flag
2155 NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name()));
2156 }
2157 }
2158
2159
2160 // Interrupt thread so it will wake up from a potential wait()
2161 Thread::interrupt(this);
2162 }
2163
2164 // External suspension mechanism.
2165 //
2166 // Tell the VM to suspend a thread when ever it knows that it does not hold on
2167 // to any VM_locks and it is at a transition
2168 // Self-suspension will happen on the transition out of the vm.
2169 // Catch "this" coming in from JNIEnv pointers when the thread has been freed
2170 //
2171 // Guarantees on return:
2172 // + Target thread will not execute any new bytecode (that's why we need to
2173 // force a safepoint)
2174 // + Target thread will not enter any new monitors
2175 //
2176 void JavaThread::java_suspend() {
2177 { MutexLocker mu(Threads_lock);
2178 if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) {
2179 return;
2180 }
2181 }
2182
2183 { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2184 if (!is_external_suspend()) {
2185 // a racing resume has cancelled us; bail out now
2186 return;
2187 }
2188
2189 // suspend is done
2190 uint32_t debug_bits = 0;
2191 // Warning: is_ext_suspend_completed() may temporarily drop the
2192 // SR_lock to allow the thread to reach a stable thread state if
2193 // it is currently in a transient thread state.
2194 if (is_ext_suspend_completed(false /* !called_by_wait */,
2195 SuspendRetryDelay, &debug_bits)) {
2196 return;
2197 }
2198 }
2199
2200 VM_ForceSafepoint vm_suspend;
2201 VMThread::execute(&vm_suspend);
2202 }
2203
2204 // Part II of external suspension.
2205 // A JavaThread self suspends when it detects a pending external suspend
2206 // request. This is usually on transitions. It is also done in places
2207 // where continuing to the next transition would surprise the caller,
2208 // e.g., monitor entry.
2209 //
2210 // Returns the number of times that the thread self-suspended.
2211 //
2212 // Note: DO NOT call java_suspend_self() when you just want to block current
2213 // thread. java_suspend_self() is the second stage of cooperative
2214 // suspension for external suspend requests and should only be used
2215 // to complete an external suspend request.
2216 //
2217 int JavaThread::java_suspend_self() {
2218 int ret = 0;
2219
2220 // we are in the process of exiting so don't suspend
2221 if (is_exiting()) {
2222 clear_external_suspend();
2223 return ret;
2224 }
2225
2226 assert(_anchor.walkable() ||
2227 (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()),
2228 "must have walkable stack");
2229
2230 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2231
2232 assert(!this->is_ext_suspended(),
2233 "a thread trying to self-suspend should not already be suspended");
2234
2235 if (this->is_suspend_equivalent()) {
2236 // If we are self-suspending as a result of the lifting of a
2237 // suspend equivalent condition, then the suspend_equivalent
2238 // flag is not cleared until we set the ext_suspended flag so
2239 // that wait_for_ext_suspend_completion() returns consistent
2240 // results.
2241 this->clear_suspend_equivalent();
2242 }
2243
2244 // A racing resume may have cancelled us before we grabbed SR_lock
2245 // above. Or another external suspend request could be waiting for us
2246 // by the time we return from SR_lock()->wait(). The thread
2247 // that requested the suspension may already be trying to walk our
2248 // stack and if we return now, we can change the stack out from under
2249 // it. This would be a "bad thing (TM)" and cause the stack walker
2250 // to crash. We stay self-suspended until there are no more pending
2251 // external suspend requests.
2252 while (is_external_suspend()) {
2253 ret++;
2254 this->set_ext_suspended();
2255
2256 // _ext_suspended flag is cleared by java_resume()
2257 while (is_ext_suspended()) {
2258 this->SR_lock()->wait(Mutex::_no_safepoint_check_flag);
2259 }
2260 }
2261
2262 return ret;
2263 }
2264
2265 #ifdef ASSERT
2266 // verify the JavaThread has not yet been published in the Threads::list, and
2267 // hence doesn't need protection from concurrent access at this stage
2268 void JavaThread::verify_not_published() {
2269 if (!Threads_lock->owned_by_self()) {
2270 MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag);
2271 assert(!Threads::includes(this),
2272 "java thread shouldn't have been published yet!");
2273 } else {
2274 assert(!Threads::includes(this),
2275 "java thread shouldn't have been published yet!");
2276 }
2277 }
2278 #endif
2279
2280 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2281 // progress or when _suspend_flags is non-zero.
2282 // Current thread needs to self-suspend if there is a suspend request and/or
2283 // block if a safepoint is in progress.
2284 // Async exception ISN'T checked.
2285 // Note only the ThreadInVMfromNative transition can call this function
2286 // directly and when thread state is _thread_in_native_trans
2287 void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) {
2288 assert(thread->thread_state() == _thread_in_native_trans, "wrong state");
2289
2290 JavaThread *curJT = JavaThread::current();
2291 bool do_self_suspend = thread->is_external_suspend();
2292
2293 assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition");
2294
2295 // If JNIEnv proxies are allowed, don't self-suspend if the target
2296 // thread is not the current thread. In older versions of jdbx, jdbx
2297 // threads could call into the VM with another thread's JNIEnv so we
2298 // can be here operating on behalf of a suspended thread (4432884).
2299 if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) {
2300 JavaThreadState state = thread->thread_state();
2301
2302 // We mark this thread_blocked state as a suspend-equivalent so
2303 // that a caller to is_ext_suspend_completed() won't be confused.
2304 // The suspend-equivalent state is cleared by java_suspend_self().
2305 thread->set_suspend_equivalent();
2306
2307 // If the safepoint code sees the _thread_in_native_trans state, it will
2308 // wait until the thread changes to other thread state. There is no
2309 // guarantee on how soon we can obtain the SR_lock and complete the
2310 // self-suspend request. It would be a bad idea to let safepoint wait for
2311 // too long. Temporarily change the state to _thread_blocked to
2312 // let the VM thread know that this thread is ready for GC. The problem
2313 // of changing thread state is that safepoint could happen just after
2314 // java_suspend_self() returns after being resumed, and VM thread will
2315 // see the _thread_blocked state. We must check for safepoint
2316 // after restoring the state and make sure we won't leave while a safepoint
2317 // is in progress.
2318 thread->set_thread_state(_thread_blocked);
2319 thread->java_suspend_self();
2320 thread->set_thread_state(state);
2321 // Make sure new state is seen by VM thread
2322 if (os::is_MP()) {
2323 if (UseMembar) {
2324 // Force a fence between the write above and read below
2325 OrderAccess::fence();
2326 } else {
2327 // Must use this rather than serialization page in particular on Windows
2328 InterfaceSupport::serialize_memory(thread);
2329 }
2330 }
2331 }
2332
2333 if (SafepointSynchronize::do_call_back()) {
2334 // If we are safepointing, then block the caller which may not be
2335 // the same as the target thread (see above).
2336 SafepointSynchronize::block(curJT);
2337 }
2338
2339 if (thread->is_deopt_suspend()) {
2340 thread->clear_deopt_suspend();
2341 RegisterMap map(thread, false);
2342 frame f = thread->last_frame();
2343 while (f.id() != thread->must_deopt_id() && ! f.is_first_frame()) {
2344 f = f.sender(&map);
2345 }
2346 if (f.id() == thread->must_deopt_id()) {
2347 thread->clear_must_deopt_id();
2348 f.deoptimize(thread);
2349 } else {
2350 fatal("missed deoptimization!");
2351 }
2352 }
2353 }
2354
2355 // Slow path when the native==>VM/Java barriers detect a safepoint is in
2356 // progress or when _suspend_flags is non-zero.
2357 // Current thread needs to self-suspend if there is a suspend request and/or
2358 // block if a safepoint is in progress.
2359 // Also check for pending async exception (not including unsafe access error).
2360 // Note only the native==>VM/Java barriers can call this function and when
2361 // thread state is _thread_in_native_trans.
2362 void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) {
2363 check_safepoint_and_suspend_for_native_trans(thread);
2364
2365 if (thread->has_async_exception()) {
2366 // We are in _thread_in_native_trans state, don't handle unsafe
2367 // access error since that may block.
2368 thread->check_and_handle_async_exceptions(false);
2369 }
2370 }
2371
2372 // This is a variant of the normal
2373 // check_special_condition_for_native_trans with slightly different
2374 // semantics for use by critical native wrappers. It does all the
2375 // normal checks but also performs the transition back into
2376 // thread_in_Java state. This is required so that critical natives
2377 // can potentially block and perform a GC if they are the last thread
2378 // exiting the GC_locker.
2379 void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) {
2380 check_special_condition_for_native_trans(thread);
2381
2382 // Finish the transition
2383 thread->set_thread_state(_thread_in_Java);
2384
2385 if (thread->do_critical_native_unlock()) {
2386 ThreadInVMfromJavaNoAsyncException tiv(thread);
2387 GC_locker::unlock_critical(thread);
2388 thread->clear_critical_native_unlock();
2389 }
2390 }
2391
2392 // We need to guarantee the Threads_lock here, since resumes are not
2393 // allowed during safepoint synchronization
2394 // Can only resume from an external suspension
2395 void JavaThread::java_resume() {
2396 assert_locked_or_safepoint(Threads_lock);
2397
2398 // Sanity check: thread is gone, has started exiting or the thread
2399 // was not externally suspended.
2400 if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) {
2401 return;
2402 }
2403
2404 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
2405
2406 clear_external_suspend();
2407
2408 if (is_ext_suspended()) {
2409 clear_ext_suspended();
2410 SR_lock()->notify_all();
2411 }
2412 }
2413
2414 void JavaThread::create_stack_guard_pages() {
2415 if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return;
2416 address low_addr = stack_base() - stack_size();
2417 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2418
2419 int allocate = os::allocate_stack_guard_pages();
2420 // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len);
2421
2422 if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) {
2423 warning("Attempt to allocate stack guard pages failed.");
2424 return;
2425 }
2426
2427 if (os::guard_memory((char *) low_addr, len)) {
2428 _stack_guard_state = stack_guard_enabled;
2429 } else {
2430 warning("Attempt to protect stack guard pages failed.");
2431 if (os::uncommit_memory((char *) low_addr, len)) {
2432 warning("Attempt to deallocate stack guard pages failed.");
2433 }
2434 }
2435 }
2436
2437 void JavaThread::remove_stack_guard_pages() {
2438 assert(Thread::current() == this, "from different thread");
2439 if (_stack_guard_state == stack_guard_unused) return;
2440 address low_addr = stack_base() - stack_size();
2441 size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size();
2442
2443 if (os::allocate_stack_guard_pages()) {
2444 if (os::remove_stack_guard_pages((char *) low_addr, len)) {
2445 _stack_guard_state = stack_guard_unused;
2446 } else {
2447 warning("Attempt to deallocate stack guard pages failed.");
2448 }
2449 } else {
2450 if (_stack_guard_state == stack_guard_unused) return;
2451 if (os::unguard_memory((char *) low_addr, len)) {
2452 _stack_guard_state = stack_guard_unused;
2453 } else {
2454 warning("Attempt to unprotect stack guard pages failed.");
2455 }
2456 }
2457 }
2458
2459 void JavaThread::enable_stack_yellow_zone() {
2460 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2461 assert(_stack_guard_state != stack_guard_enabled, "already enabled");
2462
2463 // The base notation is from the stacks point of view, growing downward.
2464 // We need to adjust it to work correctly with guard_memory()
2465 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2466
2467 guarantee(base < stack_base(), "Error calculating stack yellow zone");
2468 guarantee(base < os::current_stack_pointer(), "Error calculating stack yellow zone");
2469
2470 if (os::guard_memory((char *) base, stack_yellow_zone_size())) {
2471 _stack_guard_state = stack_guard_enabled;
2472 } else {
2473 warning("Attempt to guard stack yellow zone failed.");
2474 }
2475 enable_register_stack_guard();
2476 }
2477
2478 void JavaThread::disable_stack_yellow_zone() {
2479 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2480 assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled");
2481
2482 // Simply return if called for a thread that does not use guard pages.
2483 if (_stack_guard_state == stack_guard_unused) return;
2484
2485 // The base notation is from the stacks point of view, growing downward.
2486 // We need to adjust it to work correctly with guard_memory()
2487 address base = stack_yellow_zone_base() - stack_yellow_zone_size();
2488
2489 if (os::unguard_memory((char *)base, stack_yellow_zone_size())) {
2490 _stack_guard_state = stack_guard_yellow_disabled;
2491 } else {
2492 warning("Attempt to unguard stack yellow zone failed.");
2493 }
2494 disable_register_stack_guard();
2495 }
2496
2497 void JavaThread::enable_stack_red_zone() {
2498 // The base notation is from the stacks point of view, growing downward.
2499 // We need to adjust it to work correctly with guard_memory()
2500 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2501 address base = stack_red_zone_base() - stack_red_zone_size();
2502
2503 guarantee(base < stack_base(), "Error calculating stack red zone");
2504 guarantee(base < os::current_stack_pointer(), "Error calculating stack red zone");
2505
2506 if (!os::guard_memory((char *) base, stack_red_zone_size())) {
2507 warning("Attempt to guard stack red zone failed.");
2508 }
2509 }
2510
2511 void JavaThread::disable_stack_red_zone() {
2512 // The base notation is from the stacks point of view, growing downward.
2513 // We need to adjust it to work correctly with guard_memory()
2514 assert(_stack_guard_state != stack_guard_unused, "must be using guard pages.");
2515 address base = stack_red_zone_base() - stack_red_zone_size();
2516 if (!os::unguard_memory((char *)base, stack_red_zone_size())) {
2517 warning("Attempt to unguard stack red zone failed.");
2518 }
2519 }
2520
2521 void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) {
2522 // ignore is there is no stack
2523 if (!has_last_Java_frame()) return;
2524 // traverse the stack frames. Starts from top frame.
2525 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2526 frame* fr = fst.current();
2527 f(fr, fst.register_map());
2528 }
2529 }
2530
2531
2532 #ifndef PRODUCT
2533 // Deoptimization
2534 // Function for testing deoptimization
2535 void JavaThread::deoptimize() {
2536 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2537 StackFrameStream fst(this, UseBiasedLocking);
2538 bool deopt = false; // Dump stack only if a deopt actually happens.
2539 bool only_at = strlen(DeoptimizeOnlyAt) > 0;
2540 // Iterate over all frames in the thread and deoptimize
2541 for (; !fst.is_done(); fst.next()) {
2542 if (fst.current()->can_be_deoptimized()) {
2543
2544 if (only_at) {
2545 // Deoptimize only at particular bcis. DeoptimizeOnlyAt
2546 // consists of comma or carriage return separated numbers so
2547 // search for the current bci in that string.
2548 address pc = fst.current()->pc();
2549 nmethod* nm = (nmethod*) fst.current()->cb();
2550 ScopeDesc* sd = nm->scope_desc_at(pc);
2551 char buffer[8];
2552 jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci());
2553 size_t len = strlen(buffer);
2554 const char * found = strstr(DeoptimizeOnlyAt, buffer);
2555 while (found != NULL) {
2556 if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') &&
2557 (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) {
2558 // Check that the bci found is bracketed by terminators.
2559 break;
2560 }
2561 found = strstr(found + 1, buffer);
2562 }
2563 if (!found) {
2564 continue;
2565 }
2566 }
2567
2568 if (DebugDeoptimization && !deopt) {
2569 deopt = true; // One-time only print before deopt
2570 tty->print_cr("[BEFORE Deoptimization]");
2571 trace_frames();
2572 trace_stack();
2573 }
2574 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2575 }
2576 }
2577
2578 if (DebugDeoptimization && deopt) {
2579 tty->print_cr("[AFTER Deoptimization]");
2580 trace_frames();
2581 }
2582 }
2583
2584
2585 // Make zombies
2586 void JavaThread::make_zombies() {
2587 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2588 if (fst.current()->can_be_deoptimized()) {
2589 // it is a Java nmethod
2590 nmethod* nm = CodeCache::find_nmethod(fst.current()->pc());
2591 nm->make_not_entrant();
2592 }
2593 }
2594 }
2595 #endif // PRODUCT
2596
2597
2598 void JavaThread::deoptimized_wrt_marked_nmethods() {
2599 if (!has_last_Java_frame()) return;
2600 // BiasedLocking needs an updated RegisterMap for the revoke monitors pass
2601 StackFrameStream fst(this, UseBiasedLocking);
2602 for (; !fst.is_done(); fst.next()) {
2603 if (fst.current()->should_be_deoptimized()) {
2604 if (LogCompilation && xtty != NULL) {
2605 nmethod* nm = fst.current()->cb()->as_nmethod_or_null();
2606 xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'",
2607 this->name(), nm != NULL ? nm->compile_id() : -1);
2608 }
2609
2610 Deoptimization::deoptimize(this, *fst.current(), fst.register_map());
2611 }
2612 }
2613 }
2614
2615
2616 // If the caller is a NamedThread, then remember, in the current scope,
2617 // the given JavaThread in its _processed_thread field.
2618 class RememberProcessedThread: public StackObj {
2619 NamedThread* _cur_thr;
2620 public:
2621 RememberProcessedThread(JavaThread* jthr) {
2622 Thread* thread = Thread::current();
2623 if (thread->is_Named_thread()) {
2624 _cur_thr = (NamedThread *)thread;
2625 _cur_thr->set_processed_thread(jthr);
2626 } else {
2627 _cur_thr = NULL;
2628 }
2629 }
2630
2631 ~RememberProcessedThread() {
2632 if (_cur_thr) {
2633 _cur_thr->set_processed_thread(NULL);
2634 }
2635 }
2636 };
2637
2638 void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
2639 // Verify that the deferred card marks have been flushed.
2640 assert(deferred_card_mark().is_empty(), "Should be empty during GC");
2641
2642 // The ThreadProfiler oops_do is done from FlatProfiler::oops_do
2643 // since there may be more than one thread using each ThreadProfiler.
2644
2645 // Traverse the GCHandles
2646 Thread::oops_do(f, cld_f, cf);
2647
2648 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2649 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2650
2651 if (has_last_Java_frame()) {
2652 // Record JavaThread to GC thread
2653 RememberProcessedThread rpt(this);
2654
2655 // Traverse the privileged stack
2656 if (_privileged_stack_top != NULL) {
2657 _privileged_stack_top->oops_do(f);
2658 }
2659
2660 // traverse the registered growable array
2661 if (_array_for_gc != NULL) {
2662 for (int index = 0; index < _array_for_gc->length(); index++) {
2663 f->do_oop(_array_for_gc->adr_at(index));
2664 }
2665 }
2666
2667 // Traverse the monitor chunks
2668 for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) {
2669 chunk->oops_do(f);
2670 }
2671
2672 // Traverse the execution stack
2673 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2674 fst.current()->oops_do(f, cld_f, cf, fst.register_map());
2675 }
2676 }
2677
2678 // callee_target is never live across a gc point so NULL it here should
2679 // it still contain a methdOop.
2680
2681 set_callee_target(NULL);
2682
2683 assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!");
2684 // If we have deferred set_locals there might be oops waiting to be
2685 // written
2686 GrowableArray<jvmtiDeferredLocalVariableSet*>* list = deferred_locals();
2687 if (list != NULL) {
2688 for (int i = 0; i < list->length(); i++) {
2689 list->at(i)->oops_do(f);
2690 }
2691 }
2692
2693 // Traverse instance variables at the end since the GC may be moving things
2694 // around using this function
2695 f->do_oop((oop*) &_threadObj);
2696 f->do_oop((oop*) &_vm_result);
2697 f->do_oop((oop*) &_exception_oop);
2698 f->do_oop((oop*) &_pending_async_exception);
2699
2700 if (jvmti_thread_state() != NULL) {
2701 jvmti_thread_state()->oops_do(f);
2702 }
2703 }
2704
2705 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
2706 Thread::nmethods_do(cf); // (super method is a no-op)
2707
2708 assert((!has_last_Java_frame() && java_call_counter() == 0) ||
2709 (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
2710
2711 if (has_last_Java_frame()) {
2712 // Traverse the execution stack
2713 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2714 fst.current()->nmethods_do(cf);
2715 }
2716 }
2717 }
2718
2719 void JavaThread::metadata_do(void f(Metadata*)) {
2720 if (has_last_Java_frame()) {
2721 // Traverse the execution stack to call f() on the methods in the stack
2722 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
2723 fst.current()->metadata_do(f);
2724 }
2725 } else if (is_Compiler_thread()) {
2726 // need to walk ciMetadata in current compile tasks to keep alive.
2727 CompilerThread* ct = (CompilerThread*)this;
2728 if (ct->env() != NULL) {
2729 ct->env()->metadata_do(f);
2730 }
2731 }
2732 }
2733
2734 // Printing
2735 const char* _get_thread_state_name(JavaThreadState _thread_state) {
2736 switch (_thread_state) {
2737 case _thread_uninitialized: return "_thread_uninitialized";
2738 case _thread_new: return "_thread_new";
2739 case _thread_new_trans: return "_thread_new_trans";
2740 case _thread_in_native: return "_thread_in_native";
2741 case _thread_in_native_trans: return "_thread_in_native_trans";
2742 case _thread_in_vm: return "_thread_in_vm";
2743 case _thread_in_vm_trans: return "_thread_in_vm_trans";
2744 case _thread_in_Java: return "_thread_in_Java";
2745 case _thread_in_Java_trans: return "_thread_in_Java_trans";
2746 case _thread_blocked: return "_thread_blocked";
2747 case _thread_blocked_trans: return "_thread_blocked_trans";
2748 default: return "unknown thread state";
2749 }
2750 }
2751
2752 #ifndef PRODUCT
2753 void JavaThread::print_thread_state_on(outputStream *st) const {
2754 st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state));
2755 };
2756 void JavaThread::print_thread_state() const {
2757 print_thread_state_on(tty);
2758 }
2759 #endif // PRODUCT
2760
2761 // Called by Threads::print() for VM_PrintThreads operation
2762 void JavaThread::print_on(outputStream *st) const {
2763 st->print("\"%s\" ", get_thread_name());
2764 oop thread_oop = threadObj();
2765 if (thread_oop != NULL) {
2766 st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop));
2767 if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon ");
2768 st->print("prio=%d ", java_lang_Thread::priority(thread_oop));
2769 }
2770 Thread::print_on(st);
2771 // print guess for valid stack memory region (assume 4K pages); helps lock debugging
2772 st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12));
2773 if (thread_oop != NULL) {
2774 st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop));
2775 }
2776 #ifndef PRODUCT
2777 print_thread_state_on(st);
2778 _safepoint_state->print_on(st);
2779 #endif // PRODUCT
2780 }
2781
2782 // Called by fatal error handler. The difference between this and
2783 // JavaThread::print() is that we can't grab lock or allocate memory.
2784 void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const {
2785 st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen));
2786 oop thread_obj = threadObj();
2787 if (thread_obj != NULL) {
2788 if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon");
2789 }
2790 st->print(" [");
2791 st->print("%s", _get_thread_state_name(_thread_state));
2792 if (osthread()) {
2793 st->print(", id=%d", osthread()->thread_id());
2794 }
2795 st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")",
2796 _stack_base - _stack_size, _stack_base);
2797 st->print("]");
2798 return;
2799 }
2800
2801 // Verification
2802
2803 static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); }
2804
2805 void JavaThread::verify() {
2806 // Verify oops in the thread.
2807 oops_do(&VerifyOopClosure::verify_oop, NULL, NULL);
2808
2809 // Verify the stack frames.
2810 frames_do(frame_verify);
2811 }
2812
2813 // CR 6300358 (sub-CR 2137150)
2814 // Most callers of this method assume that it can't return NULL but a
2815 // thread may not have a name whilst it is in the process of attaching to
2816 // the VM - see CR 6412693, and there are places where a JavaThread can be
2817 // seen prior to having it's threadObj set (eg JNI attaching threads and
2818 // if vm exit occurs during initialization). These cases can all be accounted
2819 // for such that this method never returns NULL.
2820 const char* JavaThread::get_thread_name() const {
2821 #ifdef ASSERT
2822 // early safepoints can hit while current thread does not yet have TLS
2823 if (!SafepointSynchronize::is_at_safepoint()) {
2824 Thread *cur = Thread::current();
2825 if (!(cur->is_Java_thread() && cur == this)) {
2826 // Current JavaThreads are allowed to get their own name without
2827 // the Threads_lock.
2828 assert_locked_or_safepoint(Threads_lock);
2829 }
2830 }
2831 #endif // ASSERT
2832 return get_thread_name_string();
2833 }
2834
2835 // Returns a non-NULL representation of this thread's name, or a suitable
2836 // descriptive string if there is no set name
2837 const char* JavaThread::get_thread_name_string(char* buf, int buflen) const {
2838 const char* name_str;
2839 oop thread_obj = threadObj();
2840 if (thread_obj != NULL) {
2841 oop name = java_lang_Thread::name(thread_obj);
2842 if (name != NULL) {
2843 if (buf == NULL) {
2844 name_str = java_lang_String::as_utf8_string(name);
2845 } else {
2846 name_str = java_lang_String::as_utf8_string(name, buf, buflen);
2847 }
2848 } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306
2849 name_str = "<no-name - thread is attaching>";
2850 } else {
2851 name_str = Thread::name();
2852 }
2853 } else {
2854 name_str = Thread::name();
2855 }
2856 assert(name_str != NULL, "unexpected NULL thread name");
2857 return name_str;
2858 }
2859
2860
2861 const char* JavaThread::get_threadgroup_name() const {
2862 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2863 oop thread_obj = threadObj();
2864 if (thread_obj != NULL) {
2865 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2866 if (thread_group != NULL) {
2867 typeArrayOop name = java_lang_ThreadGroup::name(thread_group);
2868 // ThreadGroup.name can be null
2869 if (name != NULL) {
2870 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2871 return str;
2872 }
2873 }
2874 }
2875 return NULL;
2876 }
2877
2878 const char* JavaThread::get_parent_name() const {
2879 debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);)
2880 oop thread_obj = threadObj();
2881 if (thread_obj != NULL) {
2882 oop thread_group = java_lang_Thread::threadGroup(thread_obj);
2883 if (thread_group != NULL) {
2884 oop parent = java_lang_ThreadGroup::parent(thread_group);
2885 if (parent != NULL) {
2886 typeArrayOop name = java_lang_ThreadGroup::name(parent);
2887 // ThreadGroup.name can be null
2888 if (name != NULL) {
2889 const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length());
2890 return str;
2891 }
2892 }
2893 }
2894 }
2895 return NULL;
2896 }
2897
2898 ThreadPriority JavaThread::java_priority() const {
2899 oop thr_oop = threadObj();
2900 if (thr_oop == NULL) return NormPriority; // Bootstrapping
2901 ThreadPriority priority = java_lang_Thread::priority(thr_oop);
2902 assert(MinPriority <= priority && priority <= MaxPriority, "sanity check");
2903 return priority;
2904 }
2905
2906 void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) {
2907
2908 assert(Threads_lock->owner() == Thread::current(), "must have threads lock");
2909 // Link Java Thread object <-> C++ Thread
2910
2911 // Get the C++ thread object (an oop) from the JNI handle (a jthread)
2912 // and put it into a new Handle. The Handle "thread_oop" can then
2913 // be used to pass the C++ thread object to other methods.
2914
2915 // Set the Java level thread object (jthread) field of the
2916 // new thread (a JavaThread *) to C++ thread object using the
2917 // "thread_oop" handle.
2918
2919 // Set the thread field (a JavaThread *) of the
2920 // oop representing the java_lang_Thread to the new thread (a JavaThread *).
2921
2922 Handle thread_oop(Thread::current(),
2923 JNIHandles::resolve_non_null(jni_thread));
2924 assert(InstanceKlass::cast(thread_oop->klass())->is_linked(),
2925 "must be initialized");
2926 set_threadObj(thread_oop());
2927 java_lang_Thread::set_thread(thread_oop(), this);
2928
2929 if (prio == NoPriority) {
2930 prio = java_lang_Thread::priority(thread_oop());
2931 assert(prio != NoPriority, "A valid priority should be present");
2932 }
2933
2934 // Push the Java priority down to the native thread; needs Threads_lock
2935 Thread::set_priority(this, prio);
2936
2937 prepare_ext();
2938
2939 // Add the new thread to the Threads list and set it in motion.
2940 // We must have threads lock in order to call Threads::add.
2941 // It is crucial that we do not block before the thread is
2942 // added to the Threads list for if a GC happens, then the java_thread oop
2943 // will not be visited by GC.
2944 Threads::add(this);
2945 }
2946
2947 oop JavaThread::current_park_blocker() {
2948 // Support for JSR-166 locks
2949 oop thread_oop = threadObj();
2950 if (thread_oop != NULL &&
2951 JDK_Version::current().supports_thread_park_blocker()) {
2952 return java_lang_Thread::park_blocker(thread_oop);
2953 }
2954 return NULL;
2955 }
2956
2957
2958 void JavaThread::print_stack_on(outputStream* st) {
2959 if (!has_last_Java_frame()) return;
2960 ResourceMark rm;
2961 HandleMark hm;
2962
2963 RegisterMap reg_map(this);
2964 vframe* start_vf = last_java_vframe(®_map);
2965 int count = 0;
2966 for (vframe* f = start_vf; f; f = f->sender()) {
2967 if (f->is_java_frame()) {
2968 javaVFrame* jvf = javaVFrame::cast(f);
2969 java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci());
2970
2971 // Print out lock information
2972 if (JavaMonitorsInStackTrace) {
2973 jvf->print_lock_info_on(st, count);
2974 }
2975 } else {
2976 // Ignore non-Java frames
2977 }
2978
2979 // Bail-out case for too deep stacks
2980 count++;
2981 if (MaxJavaStackTraceDepth == count) return;
2982 }
2983 }
2984
2985
2986 // JVMTI PopFrame support
2987 void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) {
2988 assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments");
2989 if (in_bytes(size_in_bytes) != 0) {
2990 _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread);
2991 _popframe_preserved_args_size = in_bytes(size_in_bytes);
2992 Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size);
2993 }
2994 }
2995
2996 void* JavaThread::popframe_preserved_args() {
2997 return _popframe_preserved_args;
2998 }
2999
3000 ByteSize JavaThread::popframe_preserved_args_size() {
3001 return in_ByteSize(_popframe_preserved_args_size);
3002 }
3003
3004 WordSize JavaThread::popframe_preserved_args_size_in_words() {
3005 int sz = in_bytes(popframe_preserved_args_size());
3006 assert(sz % wordSize == 0, "argument size must be multiple of wordSize");
3007 return in_WordSize(sz / wordSize);
3008 }
3009
3010 void JavaThread::popframe_free_preserved_args() {
3011 assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice");
3012 FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args);
3013 _popframe_preserved_args = NULL;
3014 _popframe_preserved_args_size = 0;
3015 }
3016
3017 #ifndef PRODUCT
3018
3019 void JavaThread::trace_frames() {
3020 tty->print_cr("[Describe stack]");
3021 int frame_no = 1;
3022 for (StackFrameStream fst(this); !fst.is_done(); fst.next()) {
3023 tty->print(" %d. ", frame_no++);
3024 fst.current()->print_value_on(tty, this);
3025 tty->cr();
3026 }
3027 }
3028
3029 class PrintAndVerifyOopClosure: public OopClosure {
3030 protected:
3031 template <class T> inline void do_oop_work(T* p) {
3032 oop obj = oopDesc::load_decode_heap_oop(p);
3033 if (obj == NULL) return;
3034 tty->print(INTPTR_FORMAT ": ", p);
3035 if (obj->is_oop_or_null()) {
3036 if (obj->is_objArray()) {
3037 tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj);
3038 } else {
3039 obj->print();
3040 }
3041 } else {
3042 tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj);
3043 }
3044 tty->cr();
3045 }
3046 public:
3047 virtual void do_oop(oop* p) { do_oop_work(p); }
3048 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3049 };
3050
3051
3052 static void oops_print(frame* f, const RegisterMap *map) {
3053 PrintAndVerifyOopClosure print;
3054 f->print_value();
3055 f->oops_do(&print, NULL, NULL, (RegisterMap*)map);
3056 }
3057
3058 // Print our all the locations that contain oops and whether they are
3059 // valid or not. This useful when trying to find the oldest frame
3060 // where an oop has gone bad since the frame walk is from youngest to
3061 // oldest.
3062 void JavaThread::trace_oops() {
3063 tty->print_cr("[Trace oops]");
3064 frames_do(oops_print);
3065 }
3066
3067
3068 #ifdef ASSERT
3069 // Print or validate the layout of stack frames
3070 void JavaThread::print_frame_layout(int depth, bool validate_only) {
3071 ResourceMark rm;
3072 PRESERVE_EXCEPTION_MARK;
3073 FrameValues values;
3074 int frame_no = 0;
3075 for (StackFrameStream fst(this, false); !fst.is_done(); fst.next()) {
3076 fst.current()->describe(values, ++frame_no);
3077 if (depth == frame_no) break;
3078 }
3079 if (validate_only) {
3080 values.validate();
3081 } else {
3082 tty->print_cr("[Describe stack layout]");
3083 values.print(this);
3084 }
3085 }
3086 #endif
3087
3088 void JavaThread::trace_stack_from(vframe* start_vf) {
3089 ResourceMark rm;
3090 int vframe_no = 1;
3091 for (vframe* f = start_vf; f; f = f->sender()) {
3092 if (f->is_java_frame()) {
3093 javaVFrame::cast(f)->print_activation(vframe_no++);
3094 } else {
3095 f->print();
3096 }
3097 if (vframe_no > StackPrintLimit) {
3098 tty->print_cr("...<more frames>...");
3099 return;
3100 }
3101 }
3102 }
3103
3104
3105 void JavaThread::trace_stack() {
3106 if (!has_last_Java_frame()) return;
3107 ResourceMark rm;
3108 HandleMark hm;
3109 RegisterMap reg_map(this);
3110 trace_stack_from(last_java_vframe(®_map));
3111 }
3112
3113
3114 #endif // PRODUCT
3115
3116
3117 javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) {
3118 assert(reg_map != NULL, "a map must be given");
3119 frame f = last_frame();
3120 for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender()) {
3121 if (vf->is_java_frame()) return javaVFrame::cast(vf);
3122 }
3123 return NULL;
3124 }
3125
3126
3127 Klass* JavaThread::security_get_caller_class(int depth) {
3128 vframeStream vfst(this);
3129 vfst.security_get_caller_frame(depth);
3130 if (!vfst.at_end()) {
3131 return vfst.method()->method_holder();
3132 }
3133 return NULL;
3134 }
3135
3136 static void compiler_thread_entry(JavaThread* thread, TRAPS) {
3137 assert(thread->is_Compiler_thread(), "must be compiler thread");
3138 CompileBroker::compiler_thread_loop();
3139 }
3140
3141 static void sweeper_thread_entry(JavaThread* thread, TRAPS) {
3142 NMethodSweeper::sweeper_loop();
3143 }
3144
3145 // Create a CompilerThread
3146 CompilerThread::CompilerThread(CompileQueue* queue,
3147 CompilerCounters* counters)
3148 : JavaThread(&compiler_thread_entry) {
3149 _env = NULL;
3150 _log = NULL;
3151 _task = NULL;
3152 _queue = queue;
3153 _counters = counters;
3154 _buffer_blob = NULL;
3155 _compiler = NULL;
3156
3157 #ifndef PRODUCT
3158 _ideal_graph_printer = NULL;
3159 #endif
3160 }
3161
3162 // Create sweeper thread
3163 CodeCacheSweeperThread::CodeCacheSweeperThread()
3164 : JavaThread(&sweeper_thread_entry) {
3165 _scanned_nmethod = NULL;
3166 }
3167 void CodeCacheSweeperThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
3168 JavaThread::oops_do(f, cld_f, cf);
3169 if (_scanned_nmethod != NULL && cf != NULL) {
3170 // Safepoints can occur when the sweeper is scanning an nmethod so
3171 // process it here to make sure it isn't unloaded in the middle of
3172 // a scan.
3173 cf->do_code_blob(_scanned_nmethod);
3174 }
3175 }
3176
3177
3178 // ======= Threads ========
3179
3180 // The Threads class links together all active threads, and provides
3181 // operations over all threads. It is protected by its own Mutex
3182 // lock, which is also used in other contexts to protect thread
3183 // operations from having the thread being operated on from exiting
3184 // and going away unexpectedly (e.g., safepoint synchronization)
3185
3186 JavaThread* Threads::_thread_list = NULL;
3187 int Threads::_number_of_threads = 0;
3188 int Threads::_number_of_non_daemon_threads = 0;
3189 int Threads::_return_code = 0;
3190 int Threads::_thread_claim_parity = 0;
3191 size_t JavaThread::_stack_size_at_create = 0;
3192 #ifdef ASSERT
3193 bool Threads::_vm_complete = false;
3194 #endif
3195
3196 // All JavaThreads
3197 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
3198
3199 // All JavaThreads + all non-JavaThreads (i.e., every thread in the system)
3200 void Threads::threads_do(ThreadClosure* tc) {
3201 assert_locked_or_safepoint(Threads_lock);
3202 // ALL_JAVA_THREADS iterates through all JavaThreads
3203 ALL_JAVA_THREADS(p) {
3204 tc->do_thread(p);
3205 }
3206 // Someday we could have a table or list of all non-JavaThreads.
3207 // For now, just manually iterate through them.
3208 tc->do_thread(VMThread::vm_thread());
3209 Universe::heap()->gc_threads_do(tc);
3210 WatcherThread *wt = WatcherThread::watcher_thread();
3211 // Strictly speaking, the following NULL check isn't sufficient to make sure
3212 // the data for WatcherThread is still valid upon being examined. However,
3213 // considering that WatchThread terminates when the VM is on the way to
3214 // exit at safepoint, the chance of the above is extremely small. The right
3215 // way to prevent termination of WatcherThread would be to acquire
3216 // Terminator_lock, but we can't do that without violating the lock rank
3217 // checking in some cases.
3218 if (wt != NULL) {
3219 tc->do_thread(wt);
3220 }
3221
3222 // If CompilerThreads ever become non-JavaThreads, add them here
3223 }
3224
3225 void Threads::initialize_java_lang_classes(JavaThread* main_thread, TRAPS) {
3226 TraceTime timer("Initialize java.lang classes", TraceStartupTime);
3227
3228 if (EagerXrunInit && Arguments::init_libraries_at_startup()) {
3229 create_vm_init_libraries();
3230 }
3231
3232 initialize_class(vmSymbols::java_lang_String(), CHECK);
3233
3234 // Initialize java_lang.System (needed before creating the thread)
3235 initialize_class(vmSymbols::java_lang_System(), CHECK);
3236 // The VM creates & returns objects of this class. Make sure it's initialized.
3237 initialize_class(vmSymbols::java_lang_Class(), CHECK);
3238 initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK);
3239 Handle thread_group = create_initial_thread_group(CHECK);
3240 Universe::set_main_thread_group(thread_group());
3241 initialize_class(vmSymbols::java_lang_Thread(), CHECK);
3242 oop thread_object = create_initial_thread(thread_group, main_thread, CHECK);
3243 main_thread->set_threadObj(thread_object);
3244 // Set thread status to running since main thread has
3245 // been started and running.
3246 java_lang_Thread::set_thread_status(thread_object,
3247 java_lang_Thread::RUNNABLE);
3248
3249 // The VM preresolves methods to these classes. Make sure that they get initialized
3250 initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK);
3251 initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK);
3252 call_initializeSystemClass(CHECK);
3253
3254 // get the Java runtime name after java.lang.System is initialized
3255 JDK_Version::set_runtime_name(get_java_runtime_name(THREAD));
3256 JDK_Version::set_runtime_version(get_java_runtime_version(THREAD));
3257
3258 // an instance of OutOfMemory exception has been allocated earlier
3259 initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK);
3260 initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK);
3261 initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK);
3262 initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK);
3263 initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK);
3264 initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK);
3265 initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK);
3266 initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK);
3267 }
3268
3269 void Threads::initialize_jsr292_core_classes(TRAPS) {
3270 initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK);
3271 initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK);
3272 initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK);
3273 }
3274
3275 jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
3276 extern void JDK_Version_init();
3277
3278 // Preinitialize version info.
3279 VM_Version::early_initialize();
3280
3281 // Check version
3282 if (!is_supported_jni_version(args->version)) return JNI_EVERSION;
3283
3284 // Initialize the output stream module
3285 ostream_init();
3286
3287 // Process java launcher properties.
3288 Arguments::process_sun_java_launcher_properties(args);
3289
3290 // Initialize the os module before using TLS
3291 os::init();
3292
3293 // Initialize system properties.
3294 Arguments::init_system_properties();
3295
3296 // So that JDK version can be used as a discriminator when parsing arguments
3297 JDK_Version_init();
3298
3299 // Update/Initialize System properties after JDK version number is known
3300 Arguments::init_version_specific_system_properties();
3301
3302 // Parse arguments
3303 jint parse_result = Arguments::parse(args);
3304 if (parse_result != JNI_OK) return parse_result;
3305
3306 os::init_before_ergo();
3307
3308 jint ergo_result = Arguments::apply_ergo();
3309 if (ergo_result != JNI_OK) return ergo_result;
3310
3311 // Final check of all arguments after ergonomics which may change values.
3312 if (!CommandLineFlags::check_all_ranges_and_constraints()) {
3313 return JNI_EINVAL;
3314 }
3315
3316 if (PauseAtStartup) {
3317 os::pause();
3318 }
3319
3320 HOTSPOT_VM_INIT_BEGIN();
3321
3322 // Record VM creation timing statistics
3323 TraceVmCreationTime create_vm_timer;
3324 create_vm_timer.start();
3325
3326 // Timing (must come after argument parsing)
3327 TraceTime timer("Create VM", TraceStartupTime);
3328
3329 // Initialize the os module after parsing the args
3330 jint os_init_2_result = os::init_2();
3331 if (os_init_2_result != JNI_OK) return os_init_2_result;
3332
3333 jint adjust_after_os_result = Arguments::adjust_after_os();
3334 if (adjust_after_os_result != JNI_OK) return adjust_after_os_result;
3335
3336 // initialize TLS
3337 ThreadLocalStorage::init();
3338
3339 // Initialize output stream logging
3340 ostream_init_log();
3341
3342 // Convert -Xrun to -agentlib: if there is no JVM_OnLoad
3343 // Must be before create_vm_init_agents()
3344 if (Arguments::init_libraries_at_startup()) {
3345 convert_vm_init_libraries_to_agents();
3346 }
3347
3348 // Launch -agentlib/-agentpath and converted -Xrun agents
3349 if (Arguments::init_agents_at_startup()) {
3350 create_vm_init_agents();
3351 }
3352
3353 // Initialize Threads state
3354 _thread_list = NULL;
3355 _number_of_threads = 0;
3356 _number_of_non_daemon_threads = 0;
3357
3358 // Initialize global data structures and create system classes in heap
3359 vm_init_globals();
3360
3361 // Attach the main thread to this os thread
3362 JavaThread* main_thread = new JavaThread();
3363 main_thread->set_thread_state(_thread_in_vm);
3364 // must do this before set_active_handles and initialize_thread_local_storage
3365 // Note: on solaris initialize_thread_local_storage() will (indirectly)
3366 // change the stack size recorded here to one based on the java thread
3367 // stacksize. This adjusted size is what is used to figure the placement
3368 // of the guard pages.
3369 main_thread->record_stack_base_and_size();
3370 main_thread->initialize_thread_local_storage();
3371
3372 main_thread->set_active_handles(JNIHandleBlock::allocate_block());
3373
3374 if (!main_thread->set_as_starting_thread()) {
3375 vm_shutdown_during_initialization(
3376 "Failed necessary internal allocation. Out of swap space");
3377 delete main_thread;
3378 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3379 return JNI_ENOMEM;
3380 }
3381
3382 // Enable guard page *after* os::create_main_thread(), otherwise it would
3383 // crash Linux VM, see notes in os_linux.cpp.
3384 main_thread->create_stack_guard_pages();
3385
3386 // Initialize Java-Level synchronization subsystem
3387 ObjectMonitor::Initialize();
3388
3389 // Initialize global modules
3390 jint status = init_globals();
3391 if (status != JNI_OK) {
3392 delete main_thread;
3393 *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again
3394 return status;
3395 }
3396
3397 // Should be done after the heap is fully created
3398 main_thread->cache_global_variables();
3399
3400 HandleMark hm;
3401
3402 { MutexLocker mu(Threads_lock);
3403 Threads::add(main_thread);
3404 }
3405
3406 // Any JVMTI raw monitors entered in onload will transition into
3407 // real raw monitor. VM is setup enough here for raw monitor enter.
3408 JvmtiExport::transition_pending_onload_raw_monitors();
3409
3410 // Create the VMThread
3411 { TraceTime timer("Start VMThread", TraceStartupTime);
3412 VMThread::create();
3413 Thread* vmthread = VMThread::vm_thread();
3414
3415 if (!os::create_thread(vmthread, os::vm_thread)) {
3416 vm_exit_during_initialization("Cannot create VM thread. "
3417 "Out of system resources.");
3418 }
3419
3420 // Wait for the VM thread to become ready, and VMThread::run to initialize
3421 // Monitors can have spurious returns, must always check another state flag
3422 {
3423 MutexLocker ml(Notify_lock);
3424 os::start_thread(vmthread);
3425 while (vmthread->active_handles() == NULL) {
3426 Notify_lock->wait();
3427 }
3428 }
3429 }
3430
3431 assert(Universe::is_fully_initialized(), "not initialized");
3432 if (VerifyDuringStartup) {
3433 // Make sure we're starting with a clean slate.
3434 VM_Verify verify_op;
3435 VMThread::execute(&verify_op);
3436 }
3437
3438 Thread* THREAD = Thread::current();
3439
3440 // At this point, the Universe is initialized, but we have not executed
3441 // any byte code. Now is a good time (the only time) to dump out the
3442 // internal state of the JVM for sharing.
3443 if (DumpSharedSpaces) {
3444 MetaspaceShared::preload_and_dump(CHECK_JNI_ERR);
3445 ShouldNotReachHere();
3446 }
3447
3448 // Always call even when there are not JVMTI environments yet, since environments
3449 // may be attached late and JVMTI must track phases of VM execution
3450 JvmtiExport::enter_start_phase();
3451
3452 // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents.
3453 JvmtiExport::post_vm_start();
3454
3455 initialize_java_lang_classes(main_thread, CHECK_JNI_ERR);
3456
3457 // We need this for ClassDataSharing - the initial vm.info property is set
3458 // with the default value of CDS "sharing" which may be reset through
3459 // command line options.
3460 reset_vm_info_property(CHECK_JNI_ERR);
3461
3462 quicken_jni_functions();
3463
3464 // Must be run after init_ft which initializes ft_enabled
3465 if (TRACE_INITIALIZE() != JNI_OK) {
3466 vm_exit_during_initialization("Failed to initialize tracing backend");
3467 }
3468
3469 // Set flag that basic initialization has completed. Used by exceptions and various
3470 // debug stuff, that does not work until all basic classes have been initialized.
3471 set_init_completed();
3472
3473 Metaspace::post_initialize();
3474
3475 HOTSPOT_VM_INIT_END();
3476
3477 // record VM initialization completion time
3478 #if INCLUDE_MANAGEMENT
3479 Management::record_vm_init_completed();
3480 #endif // INCLUDE_MANAGEMENT
3481
3482 // Compute system loader. Note that this has to occur after set_init_completed, since
3483 // valid exceptions may be thrown in the process.
3484 // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and
3485 // set_init_completed has just been called, causing exceptions not to be shortcut
3486 // anymore. We call vm_exit_during_initialization directly instead.
3487 SystemDictionary::compute_java_system_loader(CHECK_JNI_ERR);
3488
3489 #if INCLUDE_ALL_GCS
3490 // Support for ConcurrentMarkSweep. This should be cleaned up
3491 // and better encapsulated. The ugly nested if test would go away
3492 // once things are properly refactored. XXX YSR
3493 if (UseConcMarkSweepGC || UseG1GC) {
3494 if (UseConcMarkSweepGC) {
3495 ConcurrentMarkSweepThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3496 } else {
3497 ConcurrentMarkThread::makeSurrogateLockerThread(CHECK_JNI_ERR);
3498 }
3499 }
3500 #endif // INCLUDE_ALL_GCS
3501
3502 // Always call even when there are not JVMTI environments yet, since environments
3503 // may be attached late and JVMTI must track phases of VM execution
3504 JvmtiExport::enter_live_phase();
3505
3506 // Signal Dispatcher needs to be started before VMInit event is posted
3507 os::signal_init();
3508
3509 // Start Attach Listener if +StartAttachListener or it can't be started lazily
3510 if (!DisableAttachMechanism) {
3511 AttachListener::vm_start();
3512 if (StartAttachListener || AttachListener::init_at_startup()) {
3513 AttachListener::init();
3514 }
3515 }
3516
3517 // Launch -Xrun agents
3518 // Must be done in the JVMTI live phase so that for backward compatibility the JDWP
3519 // back-end can launch with -Xdebug -Xrunjdwp.
3520 if (!EagerXrunInit && Arguments::init_libraries_at_startup()) {
3521 create_vm_init_libraries();
3522 }
3523
3524 // Notify JVMTI agents that VM initialization is complete - nop if no agents.
3525 JvmtiExport::post_vm_initialized();
3526
3527 if (TRACE_START() != JNI_OK) {
3528 vm_exit_during_initialization("Failed to start tracing backend.");
3529 }
3530
3531 if (CleanChunkPoolAsync) {
3532 Chunk::start_chunk_pool_cleaner_task();
3533 }
3534
3535 // initialize compiler(s)
3536 #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK)
3537 CompileBroker::compilation_init();
3538 #endif
3539
3540 // Pre-initialize some JSR292 core classes to avoid deadlock during class loading.
3541 // It is done after compilers are initialized, because otherwise compilations of
3542 // signature polymorphic MH intrinsics can be missed
3543 // (see SystemDictionary::find_method_handle_intrinsic).
3544 initialize_jsr292_core_classes(CHECK_JNI_ERR);
3545
3546 #if INCLUDE_MANAGEMENT
3547 Management::initialize(THREAD);
3548
3549 if (HAS_PENDING_EXCEPTION) {
3550 // management agent fails to start possibly due to
3551 // configuration problem and is responsible for printing
3552 // stack trace if appropriate. Simply exit VM.
3553 vm_exit(1);
3554 }
3555 #endif // INCLUDE_MANAGEMENT
3556
3557 if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true);
3558 if (MemProfiling) MemProfiler::engage();
3559 StatSampler::engage();
3560 if (CheckJNICalls) JniPeriodicChecker::engage();
3561
3562 BiasedLocking::init();
3563
3564 #if INCLUDE_RTM_OPT
3565 RTMLockingCounters::init();
3566 #endif
3567
3568 if (JDK_Version::current().post_vm_init_hook_enabled()) {
3569 call_postVMInitHook(THREAD);
3570 // The Java side of PostVMInitHook.run must deal with all
3571 // exceptions and provide means of diagnosis.
3572 if (HAS_PENDING_EXCEPTION) {
3573 CLEAR_PENDING_EXCEPTION;
3574 }
3575 }
3576
3577 {
3578 MutexLocker ml(PeriodicTask_lock);
3579 // Make sure the WatcherThread can be started by WatcherThread::start()
3580 // or by dynamic enrollment.
3581 WatcherThread::make_startable();
3582 // Start up the WatcherThread if there are any periodic tasks
3583 // NOTE: All PeriodicTasks should be registered by now. If they
3584 // aren't, late joiners might appear to start slowly (we might
3585 // take a while to process their first tick).
3586 if (PeriodicTask::num_tasks() > 0) {
3587 WatcherThread::start();
3588 }
3589 }
3590
3591 CodeCacheExtensions::complete_step(CodeCacheExtensionsSteps::CreateVM);
3592
3593 create_vm_timer.end();
3594 #ifdef ASSERT
3595 _vm_complete = true;
3596 #endif
3597 return JNI_OK;
3598 }
3599
3600 // type for the Agent_OnLoad and JVM_OnLoad entry points
3601 extern "C" {
3602 typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *);
3603 }
3604 // Find a command line agent library and return its entry point for
3605 // -agentlib: -agentpath: -Xrun
3606 // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array.
3607 static OnLoadEntry_t lookup_on_load(AgentLibrary* agent,
3608 const char *on_load_symbols[],
3609 size_t num_symbol_entries) {
3610 OnLoadEntry_t on_load_entry = NULL;
3611 void *library = NULL;
3612
3613 if (!agent->valid()) {
3614 char buffer[JVM_MAXPATHLEN];
3615 char ebuf[1024] = "";
3616 const char *name = agent->name();
3617 const char *msg = "Could not find agent library ";
3618
3619 // First check to see if agent is statically linked into executable
3620 if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) {
3621 library = agent->os_lib();
3622 } else if (agent->is_absolute_path()) {
3623 library = os::dll_load(name, ebuf, sizeof ebuf);
3624 if (library == NULL) {
3625 const char *sub_msg = " in absolute path, with error: ";
3626 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3627 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3628 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3629 // If we can't find the agent, exit.
3630 vm_exit_during_initialization(buf, NULL);
3631 FREE_C_HEAP_ARRAY(char, buf);
3632 }
3633 } else {
3634 // Try to load the agent from the standard dll directory
3635 if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(),
3636 name)) {
3637 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3638 }
3639 if (library == NULL) { // Try the local directory
3640 char ns[1] = {0};
3641 if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) {
3642 library = os::dll_load(buffer, ebuf, sizeof ebuf);
3643 }
3644 if (library == NULL) {
3645 const char *sub_msg = " on the library path, with error: ";
3646 size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1;
3647 char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread);
3648 jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf);
3649 // If we can't find the agent, exit.
3650 vm_exit_during_initialization(buf, NULL);
3651 FREE_C_HEAP_ARRAY(char, buf);
3652 }
3653 }
3654 }
3655 agent->set_os_lib(library);
3656 agent->set_valid();
3657 }
3658
3659 // Find the OnLoad function.
3660 on_load_entry =
3661 CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent,
3662 false,
3663 on_load_symbols,
3664 num_symbol_entries));
3665 return on_load_entry;
3666 }
3667
3668 // Find the JVM_OnLoad entry point
3669 static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) {
3670 const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS;
3671 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3672 }
3673
3674 // Find the Agent_OnLoad entry point
3675 static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) {
3676 const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS;
3677 return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*));
3678 }
3679
3680 // For backwards compatibility with -Xrun
3681 // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be
3682 // treated like -agentpath:
3683 // Must be called before agent libraries are created
3684 void Threads::convert_vm_init_libraries_to_agents() {
3685 AgentLibrary* agent;
3686 AgentLibrary* next;
3687
3688 for (agent = Arguments::libraries(); agent != NULL; agent = next) {
3689 next = agent->next(); // cache the next agent now as this agent may get moved off this list
3690 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3691
3692 // If there is an JVM_OnLoad function it will get called later,
3693 // otherwise see if there is an Agent_OnLoad
3694 if (on_load_entry == NULL) {
3695 on_load_entry = lookup_agent_on_load(agent);
3696 if (on_load_entry != NULL) {
3697 // switch it to the agent list -- so that Agent_OnLoad will be called,
3698 // JVM_OnLoad won't be attempted and Agent_OnUnload will
3699 Arguments::convert_library_to_agent(agent);
3700 } else {
3701 vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name());
3702 }
3703 }
3704 }
3705 }
3706
3707 // Create agents for -agentlib: -agentpath: and converted -Xrun
3708 // Invokes Agent_OnLoad
3709 // Called very early -- before JavaThreads exist
3710 void Threads::create_vm_init_agents() {
3711 extern struct JavaVM_ main_vm;
3712 AgentLibrary* agent;
3713
3714 JvmtiExport::enter_onload_phase();
3715
3716 for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3717 OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent);
3718
3719 if (on_load_entry != NULL) {
3720 // Invoke the Agent_OnLoad function
3721 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3722 if (err != JNI_OK) {
3723 vm_exit_during_initialization("agent library failed to init", agent->name());
3724 }
3725 } else {
3726 vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name());
3727 }
3728 }
3729 JvmtiExport::enter_primordial_phase();
3730 }
3731
3732 extern "C" {
3733 typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *);
3734 }
3735
3736 void Threads::shutdown_vm_agents() {
3737 // Send any Agent_OnUnload notifications
3738 const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS;
3739 size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols);
3740 extern struct JavaVM_ main_vm;
3741 for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) {
3742
3743 // Find the Agent_OnUnload function.
3744 Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t,
3745 os::find_agent_function(agent,
3746 false,
3747 on_unload_symbols,
3748 num_symbol_entries));
3749
3750 // Invoke the Agent_OnUnload function
3751 if (unload_entry != NULL) {
3752 JavaThread* thread = JavaThread::current();
3753 ThreadToNativeFromVM ttn(thread);
3754 HandleMark hm(thread);
3755 (*unload_entry)(&main_vm);
3756 }
3757 }
3758 }
3759
3760 // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries
3761 // Invokes JVM_OnLoad
3762 void Threads::create_vm_init_libraries() {
3763 extern struct JavaVM_ main_vm;
3764 AgentLibrary* agent;
3765
3766 for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) {
3767 OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent);
3768
3769 if (on_load_entry != NULL) {
3770 // Invoke the JVM_OnLoad function
3771 JavaThread* thread = JavaThread::current();
3772 ThreadToNativeFromVM ttn(thread);
3773 HandleMark hm(thread);
3774 jint err = (*on_load_entry)(&main_vm, agent->options(), NULL);
3775 if (err != JNI_OK) {
3776 vm_exit_during_initialization("-Xrun library failed to init", agent->name());
3777 }
3778 } else {
3779 vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name());
3780 }
3781 }
3782 }
3783
3784 JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) {
3785 assert(Threads_lock->owned_by_self(), "Must hold Threads_lock");
3786
3787 JavaThread* java_thread = NULL;
3788 // Sequential search for now. Need to do better optimization later.
3789 for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) {
3790 oop tobj = thread->threadObj();
3791 if (!thread->is_exiting() &&
3792 tobj != NULL &&
3793 java_tid == java_lang_Thread::thread_id(tobj)) {
3794 java_thread = thread;
3795 break;
3796 }
3797 }
3798 return java_thread;
3799 }
3800
3801
3802 // Last thread running calls java.lang.Shutdown.shutdown()
3803 void JavaThread::invoke_shutdown_hooks() {
3804 HandleMark hm(this);
3805
3806 // We could get here with a pending exception, if so clear it now.
3807 if (this->has_pending_exception()) {
3808 this->clear_pending_exception();
3809 }
3810
3811 EXCEPTION_MARK;
3812 Klass* k =
3813 SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(),
3814 THREAD);
3815 if (k != NULL) {
3816 // SystemDictionary::resolve_or_null will return null if there was
3817 // an exception. If we cannot load the Shutdown class, just don't
3818 // call Shutdown.shutdown() at all. This will mean the shutdown hooks
3819 // and finalizers (if runFinalizersOnExit is set) won't be run.
3820 // Note that if a shutdown hook was registered or runFinalizersOnExit
3821 // was called, the Shutdown class would have already been loaded
3822 // (Runtime.addShutdownHook and runFinalizersOnExit will load it).
3823 instanceKlassHandle shutdown_klass (THREAD, k);
3824 JavaValue result(T_VOID);
3825 JavaCalls::call_static(&result,
3826 shutdown_klass,
3827 vmSymbols::shutdown_method_name(),
3828 vmSymbols::void_method_signature(),
3829 THREAD);
3830 }
3831 CLEAR_PENDING_EXCEPTION;
3832 }
3833
3834 // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when
3835 // the program falls off the end of main(). Another VM exit path is through
3836 // vm_exit() when the program calls System.exit() to return a value or when
3837 // there is a serious error in VM. The two shutdown paths are not exactly
3838 // the same, but they share Shutdown.shutdown() at Java level and before_exit()
3839 // and VM_Exit op at VM level.
3840 //
3841 // Shutdown sequence:
3842 // + Shutdown native memory tracking if it is on
3843 // + Wait until we are the last non-daemon thread to execute
3844 // <-- every thing is still working at this moment -->
3845 // + Call java.lang.Shutdown.shutdown(), which will invoke Java level
3846 // shutdown hooks, run finalizers if finalization-on-exit
3847 // + Call before_exit(), prepare for VM exit
3848 // > run VM level shutdown hooks (they are registered through JVM_OnExit(),
3849 // currently the only user of this mechanism is File.deleteOnExit())
3850 // > stop flat profiler, StatSampler, watcher thread, CMS threads,
3851 // post thread end and vm death events to JVMTI,
3852 // stop signal thread
3853 // + Call JavaThread::exit(), it will:
3854 // > release JNI handle blocks, remove stack guard pages
3855 // > remove this thread from Threads list
3856 // <-- no more Java code from this thread after this point -->
3857 // + Stop VM thread, it will bring the remaining VM to a safepoint and stop
3858 // the compiler threads at safepoint
3859 // <-- do not use anything that could get blocked by Safepoint -->
3860 // + Disable tracing at JNI/JVM barriers
3861 // + Set _vm_exited flag for threads that are still running native code
3862 // + Delete this thread
3863 // + Call exit_globals()
3864 // > deletes tty
3865 // > deletes PerfMemory resources
3866 // + Return to caller
3867
3868 bool Threads::destroy_vm() {
3869 JavaThread* thread = JavaThread::current();
3870
3871 #ifdef ASSERT
3872 _vm_complete = false;
3873 #endif
3874 // Wait until we are the last non-daemon thread to execute
3875 { MutexLocker nu(Threads_lock);
3876 while (Threads::number_of_non_daemon_threads() > 1)
3877 // This wait should make safepoint checks, wait without a timeout,
3878 // and wait as a suspend-equivalent condition.
3879 //
3880 // Note: If the FlatProfiler is running and this thread is waiting
3881 // for another non-daemon thread to finish, then the FlatProfiler
3882 // is waiting for the external suspend request on this thread to
3883 // complete. wait_for_ext_suspend_completion() will eventually
3884 // timeout, but that takes time. Making this wait a suspend-
3885 // equivalent condition solves that timeout problem.
3886 //
3887 Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0,
3888 Mutex::_as_suspend_equivalent_flag);
3889 }
3890
3891 // Hang forever on exit if we are reporting an error.
3892 if (ShowMessageBoxOnError && is_error_reported()) {
3893 os::infinite_sleep();
3894 }
3895 os::wait_for_keypress_at_exit();
3896
3897 // run Java level shutdown hooks
3898 thread->invoke_shutdown_hooks();
3899
3900 before_exit(thread);
3901
3902 thread->exit(true);
3903
3904 // Stop VM thread.
3905 {
3906 // 4945125 The vm thread comes to a safepoint during exit.
3907 // GC vm_operations can get caught at the safepoint, and the
3908 // heap is unparseable if they are caught. Grab the Heap_lock
3909 // to prevent this. The GC vm_operations will not be able to
3910 // queue until after the vm thread is dead. After this point,
3911 // we'll never emerge out of the safepoint before the VM exits.
3912
3913 MutexLocker ml(Heap_lock);
3914
3915 VMThread::wait_for_vm_thread_exit();
3916 assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint");
3917 VMThread::destroy();
3918 }
3919
3920 // clean up ideal graph printers
3921 #if defined(COMPILER2) && !defined(PRODUCT)
3922 IdealGraphPrinter::clean_up();
3923 #endif
3924
3925 // Now, all Java threads are gone except daemon threads. Daemon threads
3926 // running Java code or in VM are stopped by the Safepoint. However,
3927 // daemon threads executing native code are still running. But they
3928 // will be stopped at native=>Java/VM barriers. Note that we can't
3929 // simply kill or suspend them, as it is inherently deadlock-prone.
3930
3931 #ifndef PRODUCT
3932 // disable function tracing at JNI/JVM barriers
3933 TraceJNICalls = false;
3934 TraceJVMCalls = false;
3935 TraceRuntimeCalls = false;
3936 #endif
3937
3938 VM_Exit::set_vm_exited();
3939
3940 notify_vm_shutdown();
3941
3942 delete thread;
3943
3944 // exit_globals() will delete tty
3945 exit_globals();
3946
3947 return true;
3948 }
3949
3950
3951 jboolean Threads::is_supported_jni_version_including_1_1(jint version) {
3952 if (version == JNI_VERSION_1_1) return JNI_TRUE;
3953 return is_supported_jni_version(version);
3954 }
3955
3956
3957 jboolean Threads::is_supported_jni_version(jint version) {
3958 if (version == JNI_VERSION_1_2) return JNI_TRUE;
3959 if (version == JNI_VERSION_1_4) return JNI_TRUE;
3960 if (version == JNI_VERSION_1_6) return JNI_TRUE;
3961 if (version == JNI_VERSION_1_8) return JNI_TRUE;
3962 return JNI_FALSE;
3963 }
3964
3965
3966 void Threads::add(JavaThread* p, bool force_daemon) {
3967 // The threads lock must be owned at this point
3968 assert_locked_or_safepoint(Threads_lock);
3969
3970 // See the comment for this method in thread.hpp for its purpose and
3971 // why it is called here.
3972 p->initialize_queues();
3973 p->set_next(_thread_list);
3974 _thread_list = p;
3975 _number_of_threads++;
3976 oop threadObj = p->threadObj();
3977 bool daemon = true;
3978 // Bootstrapping problem: threadObj can be null for initial
3979 // JavaThread (or for threads attached via JNI)
3980 if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) {
3981 _number_of_non_daemon_threads++;
3982 daemon = false;
3983 }
3984
3985 ThreadService::add_thread(p, daemon);
3986
3987 // Possible GC point.
3988 Events::log(p, "Thread added: " INTPTR_FORMAT, p);
3989 }
3990
3991 void Threads::remove(JavaThread* p) {
3992 // Extra scope needed for Thread_lock, so we can check
3993 // that we do not remove thread without safepoint code notice
3994 { MutexLocker ml(Threads_lock);
3995
3996 assert(includes(p), "p must be present");
3997
3998 JavaThread* current = _thread_list;
3999 JavaThread* prev = NULL;
4000
4001 while (current != p) {
4002 prev = current;
4003 current = current->next();
4004 }
4005
4006 if (prev) {
4007 prev->set_next(current->next());
4008 } else {
4009 _thread_list = p->next();
4010 }
4011 _number_of_threads--;
4012 oop threadObj = p->threadObj();
4013 bool daemon = true;
4014 if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) {
4015 _number_of_non_daemon_threads--;
4016 daemon = false;
4017
4018 // Only one thread left, do a notify on the Threads_lock so a thread waiting
4019 // on destroy_vm will wake up.
4020 if (number_of_non_daemon_threads() == 1) {
4021 Threads_lock->notify_all();
4022 }
4023 }
4024 ThreadService::remove_thread(p, daemon);
4025
4026 // Make sure that safepoint code disregard this thread. This is needed since
4027 // the thread might mess around with locks after this point. This can cause it
4028 // to do callbacks into the safepoint code. However, the safepoint code is not aware
4029 // of this thread since it is removed from the queue.
4030 p->set_terminated_value();
4031 } // unlock Threads_lock
4032
4033 // Since Events::log uses a lock, we grab it outside the Threads_lock
4034 Events::log(p, "Thread exited: " INTPTR_FORMAT, p);
4035 }
4036
4037 // Threads_lock must be held when this is called (or must be called during a safepoint)
4038 bool Threads::includes(JavaThread* p) {
4039 assert(Threads_lock->is_locked(), "sanity check");
4040 ALL_JAVA_THREADS(q) {
4041 if (q == p) {
4042 return true;
4043 }
4044 }
4045 return false;
4046 }
4047
4048 // Operations on the Threads list for GC. These are not explicitly locked,
4049 // but the garbage collector must provide a safe context for them to run.
4050 // In particular, these things should never be called when the Threads_lock
4051 // is held by some other thread. (Note: the Safepoint abstraction also
4052 // uses the Threads_lock to guarantee this property. It also makes sure that
4053 // all threads gets blocked when exiting or starting).
4054
4055 void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4056 ALL_JAVA_THREADS(p) {
4057 p->oops_do(f, cld_f, cf);
4058 }
4059 VMThread::vm_thread()->oops_do(f, cld_f, cf);
4060 }
4061
4062 void Threads::change_thread_claim_parity() {
4063 // Set the new claim parity.
4064 assert(_thread_claim_parity >= 0 && _thread_claim_parity <= 2,
4065 "Not in range.");
4066 _thread_claim_parity++;
4067 if (_thread_claim_parity == 3) _thread_claim_parity = 1;
4068 assert(_thread_claim_parity >= 1 && _thread_claim_parity <= 2,
4069 "Not in range.");
4070 }
4071
4072 #ifdef ASSERT
4073 void Threads::assert_all_threads_claimed() {
4074 ALL_JAVA_THREADS(p) {
4075 const int thread_parity = p->oops_do_parity();
4076 assert((thread_parity == _thread_claim_parity),
4077 err_msg("Thread " PTR_FORMAT " has incorrect parity %d != %d", p2i(p), thread_parity, _thread_claim_parity));
4078 }
4079 }
4080 #endif // ASSERT
4081
4082 void Threads::possibly_parallel_oops_do(bool is_par, OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) {
4083 int cp = Threads::thread_claim_parity();
4084 ALL_JAVA_THREADS(p) {
4085 if (p->claim_oops_do(is_par, cp)) {
4086 p->oops_do(f, cld_f, cf);
4087 }
4088 }
4089 VMThread* vmt = VMThread::vm_thread();
4090 if (vmt->claim_oops_do(is_par, cp)) {
4091 vmt->oops_do(f, cld_f, cf);
4092 }
4093 }
4094
4095 #if INCLUDE_ALL_GCS
4096 // Used by ParallelScavenge
4097 void Threads::create_thread_roots_tasks(GCTaskQueue* q) {
4098 ALL_JAVA_THREADS(p) {
4099 q->enqueue(new ThreadRootsTask(p));
4100 }
4101 q->enqueue(new ThreadRootsTask(VMThread::vm_thread()));
4102 }
4103
4104 // Used by Parallel Old
4105 void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) {
4106 ALL_JAVA_THREADS(p) {
4107 q->enqueue(new ThreadRootsMarkingTask(p));
4108 }
4109 q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread()));
4110 }
4111 #endif // INCLUDE_ALL_GCS
4112
4113 void Threads::nmethods_do(CodeBlobClosure* cf) {
4114 ALL_JAVA_THREADS(p) {
4115 p->nmethods_do(cf);
4116 }
4117 VMThread::vm_thread()->nmethods_do(cf);
4118 }
4119
4120 void Threads::metadata_do(void f(Metadata*)) {
4121 ALL_JAVA_THREADS(p) {
4122 p->metadata_do(f);
4123 }
4124 }
4125
4126 class ThreadHandlesClosure : public ThreadClosure {
4127 void (*_f)(Metadata*);
4128 public:
4129 ThreadHandlesClosure(void f(Metadata*)) : _f(f) {}
4130 virtual void do_thread(Thread* thread) {
4131 thread->metadata_handles_do(_f);
4132 }
4133 };
4134
4135 void Threads::metadata_handles_do(void f(Metadata*)) {
4136 // Only walk the Handles in Thread.
4137 ThreadHandlesClosure handles_closure(f);
4138 threads_do(&handles_closure);
4139 }
4140
4141 void Threads::deoptimized_wrt_marked_nmethods() {
4142 ALL_JAVA_THREADS(p) {
4143 p->deoptimized_wrt_marked_nmethods();
4144 }
4145 }
4146
4147
4148 // Get count Java threads that are waiting to enter the specified monitor.
4149 GrowableArray<JavaThread*>* Threads::get_pending_threads(int count,
4150 address monitor,
4151 bool doLock) {
4152 assert(doLock || SafepointSynchronize::is_at_safepoint(),
4153 "must grab Threads_lock or be at safepoint");
4154 GrowableArray<JavaThread*>* result = new GrowableArray<JavaThread*>(count);
4155
4156 int i = 0;
4157 {
4158 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4159 ALL_JAVA_THREADS(p) {
4160 if (p->is_Compiler_thread()) continue;
4161
4162 address pending = (address)p->current_pending_monitor();
4163 if (pending == monitor) { // found a match
4164 if (i < count) result->append(p); // save the first count matches
4165 i++;
4166 }
4167 }
4168 }
4169 return result;
4170 }
4171
4172
4173 JavaThread *Threads::owning_thread_from_monitor_owner(address owner,
4174 bool doLock) {
4175 assert(doLock ||
4176 Threads_lock->owned_by_self() ||
4177 SafepointSynchronize::is_at_safepoint(),
4178 "must grab Threads_lock or be at safepoint");
4179
4180 // NULL owner means not locked so we can skip the search
4181 if (owner == NULL) return NULL;
4182
4183 {
4184 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4185 ALL_JAVA_THREADS(p) {
4186 // first, see if owner is the address of a Java thread
4187 if (owner == (address)p) return p;
4188 }
4189 }
4190 // Cannot assert on lack of success here since this function may be
4191 // used by code that is trying to report useful problem information
4192 // like deadlock detection.
4193 if (UseHeavyMonitors) return NULL;
4194
4195 // If we didn't find a matching Java thread and we didn't force use of
4196 // heavyweight monitors, then the owner is the stack address of the
4197 // Lock Word in the owning Java thread's stack.
4198 //
4199 JavaThread* the_owner = NULL;
4200 {
4201 MutexLockerEx ml(doLock ? Threads_lock : NULL);
4202 ALL_JAVA_THREADS(q) {
4203 if (q->is_lock_owned(owner)) {
4204 the_owner = q;
4205 break;
4206 }
4207 }
4208 }
4209 // cannot assert on lack of success here; see above comment
4210 return the_owner;
4211 }
4212
4213 // Threads::print_on() is called at safepoint by VM_PrintThreads operation.
4214 void Threads::print_on(outputStream* st, bool print_stacks,
4215 bool internal_format, bool print_concurrent_locks) {
4216 char buf[32];
4217 st->print_cr("%s", os::local_time_string(buf, sizeof(buf)));
4218
4219 st->print_cr("Full thread dump %s (%s %s):",
4220 Abstract_VM_Version::vm_name(),
4221 Abstract_VM_Version::vm_release(),
4222 Abstract_VM_Version::vm_info_string());
4223 st->cr();
4224
4225 #if INCLUDE_SERVICES
4226 // Dump concurrent locks
4227 ConcurrentLocksDump concurrent_locks;
4228 if (print_concurrent_locks) {
4229 concurrent_locks.dump_at_safepoint();
4230 }
4231 #endif // INCLUDE_SERVICES
4232
4233 ALL_JAVA_THREADS(p) {
4234 ResourceMark rm;
4235 p->print_on(st);
4236 if (print_stacks) {
4237 if (internal_format) {
4238 p->trace_stack();
4239 } else {
4240 p->print_stack_on(st);
4241 }
4242 }
4243 st->cr();
4244 #if INCLUDE_SERVICES
4245 if (print_concurrent_locks) {
4246 concurrent_locks.print_locks_on(p, st);
4247 }
4248 #endif // INCLUDE_SERVICES
4249 }
4250
4251 VMThread::vm_thread()->print_on(st);
4252 st->cr();
4253 Universe::heap()->print_gc_threads_on(st);
4254 WatcherThread* wt = WatcherThread::watcher_thread();
4255 if (wt != NULL) {
4256 wt->print_on(st);
4257 st->cr();
4258 }
4259 CompileBroker::print_compiler_threads_on(st);
4260 st->flush();
4261 }
4262
4263 // Threads::print_on_error() is called by fatal error handler. It's possible
4264 // that VM is not at safepoint and/or current thread is inside signal handler.
4265 // Don't print stack trace, as the stack may not be walkable. Don't allocate
4266 // memory (even in resource area), it might deadlock the error handler.
4267 void Threads::print_on_error(outputStream* st, Thread* current, char* buf,
4268 int buflen) {
4269 bool found_current = false;
4270 st->print_cr("Java Threads: ( => current thread )");
4271 ALL_JAVA_THREADS(thread) {
4272 bool is_current = (current == thread);
4273 found_current = found_current || is_current;
4274
4275 st->print("%s", is_current ? "=>" : " ");
4276
4277 st->print(PTR_FORMAT, thread);
4278 st->print(" ");
4279 thread->print_on_error(st, buf, buflen);
4280 st->cr();
4281 }
4282 st->cr();
4283
4284 st->print_cr("Other Threads:");
4285 if (VMThread::vm_thread()) {
4286 bool is_current = (current == VMThread::vm_thread());
4287 found_current = found_current || is_current;
4288 st->print("%s", current == VMThread::vm_thread() ? "=>" : " ");
4289
4290 st->print(PTR_FORMAT, VMThread::vm_thread());
4291 st->print(" ");
4292 VMThread::vm_thread()->print_on_error(st, buf, buflen);
4293 st->cr();
4294 }
4295 WatcherThread* wt = WatcherThread::watcher_thread();
4296 if (wt != NULL) {
4297 bool is_current = (current == wt);
4298 found_current = found_current || is_current;
4299 st->print("%s", is_current ? "=>" : " ");
4300
4301 st->print(PTR_FORMAT, wt);
4302 st->print(" ");
4303 wt->print_on_error(st, buf, buflen);
4304 st->cr();
4305 }
4306 if (!found_current) {
4307 st->cr();
4308 st->print("=>" PTR_FORMAT " (exited) ", current);
4309 current->print_on_error(st, buf, buflen);
4310 st->cr();
4311 }
4312 }
4313
4314 // Internal SpinLock and Mutex
4315 // Based on ParkEvent
4316
4317 // Ad-hoc mutual exclusion primitives: SpinLock and Mux
4318 //
4319 // We employ SpinLocks _only for low-contention, fixed-length
4320 // short-duration critical sections where we're concerned
4321 // about native mutex_t or HotSpot Mutex:: latency.
4322 // The mux construct provides a spin-then-block mutual exclusion
4323 // mechanism.
4324 //
4325 // Testing has shown that contention on the ListLock guarding gFreeList
4326 // is common. If we implement ListLock as a simple SpinLock it's common
4327 // for the JVM to devolve to yielding with little progress. This is true
4328 // despite the fact that the critical sections protected by ListLock are
4329 // extremely short.
4330 //
4331 // TODO-FIXME: ListLock should be of type SpinLock.
4332 // We should make this a 1st-class type, integrated into the lock
4333 // hierarchy as leaf-locks. Critically, the SpinLock structure
4334 // should have sufficient padding to avoid false-sharing and excessive
4335 // cache-coherency traffic.
4336
4337
4338 typedef volatile int SpinLockT;
4339
4340 void Thread::SpinAcquire(volatile int * adr, const char * LockName) {
4341 if (Atomic::cmpxchg (1, adr, 0) == 0) {
4342 return; // normal fast-path return
4343 }
4344
4345 // Slow-path : We've encountered contention -- Spin/Yield/Block strategy.
4346 TEVENT(SpinAcquire - ctx);
4347 int ctr = 0;
4348 int Yields = 0;
4349 for (;;) {
4350 while (*adr != 0) {
4351 ++ctr;
4352 if ((ctr & 0xFFF) == 0 || !os::is_MP()) {
4353 if (Yields > 5) {
4354 os::naked_short_sleep(1);
4355 } else {
4356 os::naked_yield();
4357 ++Yields;
4358 }
4359 } else {
4360 SpinPause();
4361 }
4362 }
4363 if (Atomic::cmpxchg(1, adr, 0) == 0) return;
4364 }
4365 }
4366
4367 void Thread::SpinRelease(volatile int * adr) {
4368 assert(*adr != 0, "invariant");
4369 OrderAccess::fence(); // guarantee at least release consistency.
4370 // Roach-motel semantics.
4371 // It's safe if subsequent LDs and STs float "up" into the critical section,
4372 // but prior LDs and STs within the critical section can't be allowed
4373 // to reorder or float past the ST that releases the lock.
4374 // Loads and stores in the critical section - which appear in program
4375 // order before the store that releases the lock - must also appear
4376 // before the store that releases the lock in memory visibility order.
4377 // Conceptually we need a #loadstore|#storestore "release" MEMBAR before
4378 // the ST of 0 into the lock-word which releases the lock, so fence
4379 // more than covers this on all platforms.
4380 *adr = 0;
4381 }
4382
4383 // muxAcquire and muxRelease:
4384 //
4385 // * muxAcquire and muxRelease support a single-word lock-word construct.
4386 // The LSB of the word is set IFF the lock is held.
4387 // The remainder of the word points to the head of a singly-linked list
4388 // of threads blocked on the lock.
4389 //
4390 // * The current implementation of muxAcquire-muxRelease uses its own
4391 // dedicated Thread._MuxEvent instance. If we're interested in
4392 // minimizing the peak number of extant ParkEvent instances then
4393 // we could eliminate _MuxEvent and "borrow" _ParkEvent as long
4394 // as certain invariants were satisfied. Specifically, care would need
4395 // to be taken with regards to consuming unpark() "permits".
4396 // A safe rule of thumb is that a thread would never call muxAcquire()
4397 // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently
4398 // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could
4399 // consume an unpark() permit intended for monitorenter, for instance.
4400 // One way around this would be to widen the restricted-range semaphore
4401 // implemented in park(). Another alternative would be to provide
4402 // multiple instances of the PlatformEvent() for each thread. One
4403 // instance would be dedicated to muxAcquire-muxRelease, for instance.
4404 //
4405 // * Usage:
4406 // -- Only as leaf locks
4407 // -- for short-term locking only as muxAcquire does not perform
4408 // thread state transitions.
4409 //
4410 // Alternatives:
4411 // * We could implement muxAcquire and muxRelease with MCS or CLH locks
4412 // but with parking or spin-then-park instead of pure spinning.
4413 // * Use Taura-Oyama-Yonenzawa locks.
4414 // * It's possible to construct a 1-0 lock if we encode the lockword as
4415 // (List,LockByte). Acquire will CAS the full lockword while Release
4416 // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so
4417 // acquiring threads use timers (ParkTimed) to detect and recover from
4418 // the stranding window. Thread/Node structures must be aligned on 256-byte
4419 // boundaries by using placement-new.
4420 // * Augment MCS with advisory back-link fields maintained with CAS().
4421 // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner.
4422 // The validity of the backlinks must be ratified before we trust the value.
4423 // If the backlinks are invalid the exiting thread must back-track through the
4424 // the forward links, which are always trustworthy.
4425 // * Add a successor indication. The LockWord is currently encoded as
4426 // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable
4427 // to provide the usual futile-wakeup optimization.
4428 // See RTStt for details.
4429 // * Consider schedctl.sc_nopreempt to cover the critical section.
4430 //
4431
4432
4433 typedef volatile intptr_t MutexT; // Mux Lock-word
4434 enum MuxBits { LOCKBIT = 1 };
4435
4436 void Thread::muxAcquire(volatile intptr_t * Lock, const char * LockName) {
4437 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4438 if (w == 0) return;
4439 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4440 return;
4441 }
4442
4443 TEVENT(muxAcquire - Contention);
4444 ParkEvent * const Self = Thread::current()->_MuxEvent;
4445 assert((intptr_t(Self) & LOCKBIT) == 0, "invariant");
4446 for (;;) {
4447 int its = (os::is_MP() ? 100 : 0) + 1;
4448
4449 // Optional spin phase: spin-then-park strategy
4450 while (--its >= 0) {
4451 w = *Lock;
4452 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4453 return;
4454 }
4455 }
4456
4457 Self->reset();
4458 Self->OnList = intptr_t(Lock);
4459 // The following fence() isn't _strictly necessary as the subsequent
4460 // CAS() both serializes execution and ratifies the fetched *Lock value.
4461 OrderAccess::fence();
4462 for (;;) {
4463 w = *Lock;
4464 if ((w & LOCKBIT) == 0) {
4465 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4466 Self->OnList = 0; // hygiene - allows stronger asserts
4467 return;
4468 }
4469 continue; // Interference -- *Lock changed -- Just retry
4470 }
4471 assert(w & LOCKBIT, "invariant");
4472 Self->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4473 if (Atomic::cmpxchg_ptr(intptr_t(Self)|LOCKBIT, Lock, w) == w) break;
4474 }
4475
4476 while (Self->OnList != 0) {
4477 Self->park();
4478 }
4479 }
4480 }
4481
4482 void Thread::muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev) {
4483 intptr_t w = Atomic::cmpxchg_ptr(LOCKBIT, Lock, 0);
4484 if (w == 0) return;
4485 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4486 return;
4487 }
4488
4489 TEVENT(muxAcquire - Contention);
4490 ParkEvent * ReleaseAfter = NULL;
4491 if (ev == NULL) {
4492 ev = ReleaseAfter = ParkEvent::Allocate(NULL);
4493 }
4494 assert((intptr_t(ev) & LOCKBIT) == 0, "invariant");
4495 for (;;) {
4496 guarantee(ev->OnList == 0, "invariant");
4497 int its = (os::is_MP() ? 100 : 0) + 1;
4498
4499 // Optional spin phase: spin-then-park strategy
4500 while (--its >= 0) {
4501 w = *Lock;
4502 if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4503 if (ReleaseAfter != NULL) {
4504 ParkEvent::Release(ReleaseAfter);
4505 }
4506 return;
4507 }
4508 }
4509
4510 ev->reset();
4511 ev->OnList = intptr_t(Lock);
4512 // The following fence() isn't _strictly necessary as the subsequent
4513 // CAS() both serializes execution and ratifies the fetched *Lock value.
4514 OrderAccess::fence();
4515 for (;;) {
4516 w = *Lock;
4517 if ((w & LOCKBIT) == 0) {
4518 if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) {
4519 ev->OnList = 0;
4520 // We call ::Release while holding the outer lock, thus
4521 // artificially lengthening the critical section.
4522 // Consider deferring the ::Release() until the subsequent unlock(),
4523 // after we've dropped the outer lock.
4524 if (ReleaseAfter != NULL) {
4525 ParkEvent::Release(ReleaseAfter);
4526 }
4527 return;
4528 }
4529 continue; // Interference -- *Lock changed -- Just retry
4530 }
4531 assert(w & LOCKBIT, "invariant");
4532 ev->ListNext = (ParkEvent *) (w & ~LOCKBIT);
4533 if (Atomic::cmpxchg_ptr(intptr_t(ev)|LOCKBIT, Lock, w) == w) break;
4534 }
4535
4536 while (ev->OnList != 0) {
4537 ev->park();
4538 }
4539 }
4540 }
4541
4542 // Release() must extract a successor from the list and then wake that thread.
4543 // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme
4544 // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based
4545 // Release() would :
4546 // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list.
4547 // (B) Extract a successor from the private list "in-hand"
4548 // (C) attempt to CAS() the residual back into *Lock over null.
4549 // If there were any newly arrived threads and the CAS() would fail.
4550 // In that case Release() would detach the RATs, re-merge the list in-hand
4551 // with the RATs and repeat as needed. Alternately, Release() might
4552 // detach and extract a successor, but then pass the residual list to the wakee.
4553 // The wakee would be responsible for reattaching and remerging before it
4554 // competed for the lock.
4555 //
4556 // Both "pop" and DMR are immune from ABA corruption -- there can be
4557 // multiple concurrent pushers, but only one popper or detacher.
4558 // This implementation pops from the head of the list. This is unfair,
4559 // but tends to provide excellent throughput as hot threads remain hot.
4560 // (We wake recently run threads first).
4561 //
4562 // All paths through muxRelease() will execute a CAS.
4563 // Release consistency -- We depend on the CAS in muxRelease() to provide full
4564 // bidirectional fence/MEMBAR semantics, ensuring that all prior memory operations
4565 // executed within the critical section are complete and globally visible before the
4566 // store (CAS) to the lock-word that releases the lock becomes globally visible.
4567 void Thread::muxRelease(volatile intptr_t * Lock) {
4568 for (;;) {
4569 const intptr_t w = Atomic::cmpxchg_ptr(0, Lock, LOCKBIT);
4570 assert(w & LOCKBIT, "invariant");
4571 if (w == LOCKBIT) return;
4572 ParkEvent * const List = (ParkEvent *) (w & ~LOCKBIT);
4573 assert(List != NULL, "invariant");
4574 assert(List->OnList == intptr_t(Lock), "invariant");
4575 ParkEvent * const nxt = List->ListNext;
4576 guarantee((intptr_t(nxt) & LOCKBIT) == 0, "invariant");
4577
4578 // The following CAS() releases the lock and pops the head element.
4579 // The CAS() also ratifies the previously fetched lock-word value.
4580 if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) {
4581 continue;
4582 }
4583 List->OnList = 0;
4584 OrderAccess::fence();
4585 List->unpark();
4586 return;
4587 }
4588 }
4589
4590
4591 void Threads::verify() {
4592 ALL_JAVA_THREADS(p) {
4593 p->verify();
4594 }
4595 VMThread* thread = VMThread::vm_thread();
4596 if (thread != NULL) thread->verify();
4597 }